复杂方程计算专项练习题
孝经-淮阴师范大学
小学复杂方程专项练习题
(1)2x+5=5x﹣7,
(2)3(x﹣2)=2﹣5(x﹣2),
(3) ﹣=1,
(4)
5÷(X+16.81)=,
(5)0.2x+=8﹣x,
(6)X+(3X﹣16)÷=10(X+1),
(7)x+1=x+3,
(8)6(3x﹣2)﹣4(4x﹣3)=1﹣8x,
(9)4(x﹣2)+20x﹣4=5(1﹣2x),
(10)1.6÷(x﹣0.45)=5,
(11)
35(x﹣2)﹣15(5x﹣6)=(22x﹣63)﹣21(3x﹣4),
(12)x÷15+0.4=x÷12﹣0.1,
(13) 150.5﹣4x=7-0.5x
(14) x﹣2=0.25﹣x,
(15)
5X+7.25=12﹣2.5X,
(16)
2(x+2)﹣3=3x﹣5,
(17)
x+(3x﹣16)÷25%=10(x+1),
(18)
x﹣1.4=3.6+x,
(19)1.2:=,
(20)=8+x,
(21) 8(x﹣2)=2x+7,
(22)
6(x﹣3.5)=17.8+2x,
(23)
5÷(x+16.84)=0.2,
(24)(9+Χ):(9﹣Χ)=5:3,
(25)x+(3x﹣16)÷25%=10(x+2),
(26)(X+12)×=42﹣X,
(27)2÷(X﹣0﹒55)=,
(28)7×(x+6)﹣3x=4×(2x+5),
(29)=2.5,
(30) 60÷(x+10)=5
(31)
(28﹣2x)=6(x﹣5)
(32)
64÷(2x﹣5)=32
(34)1÷(x﹣45%)=2.8,
(35)5(X+4)=26.6﹣X,
(36)100×0.5+(x﹣100)×0.4=0.48x
(37)3(x+2)=4(x+1),
(38)(x+2)=x+1
(39)76(x﹣2)=52x﹣32
(40)81x﹣342=76(x﹣2)
(41)3(2﹣x)+5(4x﹣3)=4(x+1)
(42)15﹣(5.5﹣x)=2x
(43)16+x=12+2x+x
(44)2(x﹣4)=3(x﹣12)
(45)0.4÷(4﹣x)=1÷4
(46)8(x﹣2)=2(x+7),
(47)30%x+85=70%x+25,
(48)8.5×1.2﹣5.3x=8.5﹣4x
(49)5x﹣2(3﹣2x)=16x﹣23
(50)(x﹣5)×5﹣9=(x﹣12)×12
(51)(10﹣x)÷2=5x﹣7
(52)2.7x﹣1.8=1.2x+2.7,
(53)8﹣5(6x+0.7)=10x+0.5,
(54)8.5x﹣3.9x=55.2(x﹣18),
(55)122﹣x﹣19=(x﹣19)×5,
(56)3.5x+2=4x﹣1,
(57)=
(58)X+(3X﹣16)÷25%=10(X+1)
(59) 75÷(x+10)=2,
(60)5x﹣3×(28﹣x)=12+2x,
(61)6(x+1)=0.5(10x+16),
(62)5(x+2)=4(x+9),
(63)127.5÷(2x+3)=15,
(64)3(x+2)=4(x+1),
(65)8(x﹣1.5)=x+0.6,
(66)7(x+6)﹣3x=4(2x+5),
(67)4x﹣2(5.5﹣x)=3.5x﹣8,
(68)2.8x=19.32﹣6.4x,
(69)5(y﹣4)﹣7(7﹣y)﹣9=12﹣3(9﹣y),
(70)35(x﹣2)﹣15(5x﹣6)=22x﹣63﹣21(3x﹣4),
(71)2.6x=51.6﹣3.4x,
(72)3(4x﹣2)﹣2(3x+3)=9﹣8x,
(73)20+4x=6x﹣24,
(74)5(x﹣1)=x+1,
(75)3(3x﹣2)=10﹣0.5(x﹣3.5),
(76)0.4(x﹣0.2)+1.5=0.7x﹣0.38,
(77)(0.6x+420)÷(x+20)=3,
(78)35(2﹣x)+15(6﹣5x)=22x+7+21(4﹣3x),
(79)5(3x﹣4)﹣2(x﹣1)=5(2x﹣1)
(80) x=4.9+x,
(81)3x+5×=2x+×,
(82)X÷3.2=(18﹣x)÷5,
(83)4(4x﹣6)=5(3x+1),
(84)10X=3(2X+17)+45,
(85)5.7(X﹣0.2)=5.1(X+0.6)+4,
(86)(3x+4)+x=7(x﹣5)
(87)(9+21)x=66x÷60﹣40﹣440,
(88)x﹣2.5=(x﹣1.8)×2
(89)12+(x﹣12)×+x=x
(90)3(X﹣3)+4(3X﹣2)=7(2﹣X),
(91)﹣=﹣2,
小学复杂方程专91题参考答案:
(1)2x+5=5x﹣7,
2x+5﹣2x=5x﹣7﹣2x,
3x﹣7=5,
3x﹣7+7=5+7,
3x=12,
3x÷3=12÷3,
x=4;
(2)3(x﹣2)=2﹣5(x﹣2),
3x﹣6=12﹣5x,
3x﹣6+5x=12﹣5x+5x,
8x﹣6=12,
8x﹣6+6=12+6,
8x=18,
8x÷8=18÷8,
x=2.25;
(3) ﹣=1,
(﹣)×24=1×24,
6(y+2)﹣4(2y﹣3)=24,
30﹣2y=24,
30﹣2y+2y=24+2y,
2y+24=30,
2y+24﹣24=30﹣24,
2y=6,
2y÷2=6÷2,
y=3
(4) 5÷(X+16.81)=,
5÷(X+16.81)×(X+16.81)=×(X+16.81),
×(X+16.81)=5,
×(X+16.81)×5=5×5,
X+16.81=25,
X+16.81﹣16.81=25﹣16.81,
x=8.19
(5)0.2x+=8﹣x,
0.2x++x=8﹣x+x,
1.8x+=8,
1.8x+﹣=8﹣,
1.8x=7.2,
1.8x÷1.8=7.2÷1.8,
x=4
(6)X+(3X﹣16)÷=10(X+1),
X+(3X﹣16)×4=10X+10,
X+12X﹣64=10X+10,
13X﹣64=10X+10,
13X﹣64+64=10X+10+64,
13X=10X+74,
13X﹣10X=10X+74﹣10X,
3X=74,
3X÷3=74÷3,
X=
(7)x+1=x+3,
x+1﹣x=x+3﹣x,
x+1=3,
x+1﹣1=3﹣1,
x=2
(8)6(3x﹣2)﹣4(4x﹣3)=1﹣8x,
18x﹣12﹣16x+12=1﹣8x,
18x﹣16x+8x=0,
10x=1,
x=1÷10,
x=;
(9)4(x﹣2)+20x﹣4=5(1﹣2x),
4x﹣8+20x﹣4=5﹣10x,
24x+10x=5+12,
34x=17,
x=17÷34,
x=;
(10)1.6÷(x﹣0.45)=5,
x﹣0.45=1.6÷5,
x﹣0.45=0.32,
x=0.32+0.45,
x=0.77;
(11)
35(x﹣2)﹣15(5x﹣6)=(22x﹣63)﹣21(3x﹣4),
35x﹣70﹣75x+90=22x﹣63﹣63x+84,
35x﹣70﹣75x+90-22x+63x=22x﹣63-63x+84-22x+63x
x+20=21,
X+20-20 =21﹣20,
x=1
(12)x÷15+0.4=x÷12﹣0.1,
x+0.4=x﹣0.1,
x+0.4﹣x=x﹣0.1﹣x,
0.4+0.1=x﹣0.1+0.1,
0.5×60=x×60,
x=30;
(13) 150.5﹣4x=7-0.5x
150.5﹣4x+0.5x=7-0.5x+0.5x
150.5﹣3.5x=7,
150.5﹣3.5x+3.5x=7+3.5x,
150.5﹣7=7+3.5x﹣7,
143.5÷3.5=3.5x÷3.5,
x=41
(14) x﹣2=0.25﹣x,
x﹣2+=0.25﹣x+,
x﹣2=0.25,
x﹣2+2=0.25+2,
x×=2×,
x=4
(15) 5X+7.25=12﹣2.5X,
5X+7.25+2.5X=12﹣2.5X+2.5X,
7.5X+7.25=12,
7.5X+7.25﹣7.25=12﹣7.25,
7.5X=5,
7.5X÷7.5=5÷7.5,
X=.
(16) 2(x+2)﹣3=3x﹣5,
2x+4﹣3=3x﹣5,
2x+1+5=3x﹣5+5,
2x+6=3x,
2x+6﹣2x=3x﹣2x,
x=6.
(17) x+(3x﹣16)÷25%=10(x+1),
x+12x﹣64=10x+10,
13x﹣64=10x+10,
13x﹣64﹣10x=10x+10﹣10x,
3x﹣64+64=10+64,
3x÷3=74÷3,
x=
(18) x﹣1.4=3.6+x,
x﹣1.4﹣x=3.6+x﹣x,
x﹣1.4=3.6,
x﹣1.4+1.4=3.6+1.4,
x=5,
x=5,
x=60,
(19)1.2:=,
x=1.2×5,
x=6,
x=6,
x=9
(20)=8+x,
()×3=(8+x)×3,
5x﹣2=24+3x,
5x﹣2﹣3x=24+3x﹣3x,
2x﹣2=24,
2x﹣2+2=24+2,
2x=26,
2x÷2=26÷2,
x=13
(21) 8(x﹣2)=2x+7,
8x﹣16+16=2x+7+16,
8x=2x+23,
8x﹣2x=2x+23﹣2x,
6x=23,
6x÷6=23÷6,
x=3
(22)
6(x﹣3.5)=17.8+2x,
6x﹣21=17.8+2x,
6x﹣21﹣2x=17.8+2x﹣2x,
4x﹣21+21=17.8+21,
4x÷4=38.8÷4,
x=9.7;
(23)
5÷(x+16.84)=0.2,
5÷(x+16.84)×(x+16.84)=0.2×(x+16.84),
5=0.2x+3.368,
5﹣3.368=0.2x+3.368﹣3.368,
1.632÷0.2=0.2x÷0.2,
x=8.16;
(24)(9+Χ):(9﹣Χ)=5:3,
3(9+X)=5(9﹣X),
3×9+3X=5×9﹣5X,
27+3X=45﹣5X,
3X+5X=45﹣27,
8X=18,
8X÷8=18÷8,
X=2.25;
(25)x+(3x﹣16)÷25%=10(x+2),
x+(3x﹣16)÷=10x+10×2,
x+(3x﹣16)×4=10x+20,
x+3x×4﹣16×4=10x+20,
x+12x﹣64=10x+20,
x+12x﹣10x=20+64,
3x=84,
3x÷3=84÷3,
x=28
(26)(X+12)×=42﹣X,
X+12×=42﹣X,
X+=42﹣X,
X+﹣=42﹣X﹣,
X=﹣X,
X+X=﹣X+X,
X=,
X×=×,
X=;
(27)2÷(X﹣0﹒55)=,
2÷(X﹣0﹒55)×(X﹣0.55)=×(X﹣0.55),
×(X﹣0.55)=,
×(X﹣0.55)×=×,
X﹣0.55=,
X﹣0.55+0.55=0.46875+0.55,
X=1.01875;
(28)7×(x+6)﹣3x=4×(2x+5),
7x+42﹣3x=8x+20,
42+4x=8x+20,
4x+20=42,
4x+20﹣20=42﹣20,
4x=22,
4x÷4=22÷4,
x=5.5;
(29)=2.5,
15=2.5×(3x+5),
7.5x+12.5=15,
7.5x+12.5﹣12.5=15﹣12.5,
7.5x=2.5,
7.5x÷7.5=2.5÷7.5,
x=
(30) 60÷(x+10)=5
60÷(x+10)×(x+10)=5
(x+10)
5x+50=60
5x+50﹣50=60﹣50
5x=10
5x÷5=10÷5
x=2
(31) (28﹣2x)=6(x﹣5)
﹣x=6x﹣30
+30=6x+x
x=
x×=×
x=6
(32)
64÷(2x﹣5)=32
64÷(2x﹣5)×(2x﹣5)=32×(2x﹣5)
64x=160+64
64x=224
64x÷64=224÷64
x=3.5
(33)81x﹣342=76×(x﹣2)
81x﹣342=76×x﹣152
81x﹣76x=342﹣152
5x=190
5x÷5=190÷5
x=38
(34)1÷(x﹣45%)=2.8,
1.4÷(x﹣0.45)=2.8,
x﹣0.45=1.4÷2.8,
x﹣0.45=0.5,
x﹣0.45+0.45=0.5+0.45,
x=0.95
(35)5(X+4)=26.6﹣X,
5x+20+x=26.,6﹣x+x,
6x+20﹣20=26.6﹣20,
6x÷6=6.6÷6,
(36)100×0.5+(x﹣100)×0.4=0.48x
0.4x+10=0.48x
0.4x+10﹣0.4x=0.48x﹣0.4x
0.08x=10
0.08x÷0.08=10÷0.08
x=125.
(37)3(x+2)=4(x+1),
3x+6=4x+4,
3x+6﹣3x=4x+4﹣3x,
x+4=6,
x+4﹣4=6﹣4,
x=2
(38)(x+2)=x+1
x+=x+1
x+﹣=x+1﹣
x=x﹣
x﹣x=x﹣﹣x
x﹣=0
x﹣+=0+
x=
x×4=×4
x=2
(39)76(x﹣2)=52x﹣32
76x﹣152=52x﹣32
76x﹣152+152=52x﹣32+152
76x=52x+120
76x﹣52x=52x+120﹣52x
24x=120
24x÷24=120÷24
x=5.
(40)81x﹣342=76(x﹣2)
81x﹣342=76x﹣152,
81x﹣342+342=76x﹣152+342,
81x=76x+190
81x﹣76x=76x+190﹣76x
5x=190
5x÷5=190÷5
x=38
(41)3(2﹣x)+5(4x﹣3)=4(x+1)
6﹣3x+20x﹣15=4x+4
17x﹣9=4x+4
17x﹣4x+9﹣9=4x﹣4x+4+9
13x=13
13x÷13=13÷13
x=1;
(42)15﹣(5.5﹣x)=2x
15﹣5.5+x=2x
2x﹣x=9.5
x=9.5;
(43)16+x=12+2x+x
16+x=12+3x
3x﹣x=16﹣12
2x=4
x÷2=4÷2
x=2
(44)2(x﹣4)=3(x﹣12)
2x﹣8=3x﹣36
2x﹣8﹣2x=3x﹣2x﹣36
﹣8=x﹣36
﹣8+36=x﹣36+36
x=28;
(45)0.4÷(4﹣x)=1÷4
=
1.6=4﹣x
1.6+x=4﹣x+x
1.6+x=4
1.6+x﹣1.6=4﹣1.6
x=2.4;
(46)8(x﹣2)=2(x+7),
8x﹣16=2x+14,
8x﹣16﹣2x=2x+14﹣2x,
6x﹣16+16=14+16,
6x÷6=30÷6,
x=5
(47)30%x+85=70%x+25,
0.3x+85﹣0.3x=0.7x+25﹣0.3x,
0.4x+25=85,
0.4x+25﹣25=85﹣25,
0.4x=60,
0.4x÷0.4=60÷0.4,
x=150;
(48)8.5×1.2﹣5.3x=8.5﹣4x
10.2﹣5.3x=8.5﹣4x
10.2﹣5.3x+5.3x﹣8.5=8.5﹣4x+5.3x﹣8.5
1.3x=1.7
1.3x÷1.3=1.7÷1.3
x=
(49)5x﹣2(3﹣2x)=16x﹣23
5x﹣6+4x=16x﹣23
9x﹣6=16x﹣23
9x﹣6﹣9x+23=16x﹣23﹣9x+23
7x=17
7x÷7=17÷7
x=
(50)(x﹣5)×5﹣9=(x﹣12)×12
5x﹣25﹣9=12x﹣144
5x﹣34=12x﹣144
5x﹣34﹣5x+144=12x﹣144﹣5x+144
7x=110
7x÷7=110÷7
x=
(51)(10﹣x)÷2=5x﹣7
10﹣x=10x﹣14
10﹣x+x+14=10x﹣14+x+14
11x=24
11x÷11=24÷11
x=
(52)2.7x﹣1.8=1.2x+2.7,
2.7x﹣1.8+1.8=1.2x+2.7+1.8,
2.7x﹣1.2x=1.2x+4.5﹣1.2x,
1.5x÷1.5=4.5÷1.5,
x=3;
(53)8﹣5(6x+0.7)=10x+0.5,
8﹣30x﹣3.5=10x+0.5,
4.5﹣30x+30x=10x+0.5+30x,
4.5﹣0.5=40x﹣0.5,
4÷40=40x÷40,
x=0.1;
(54)8.5x﹣3.9x=55.2(x﹣18),
4.6x=55.2x﹣993.6,
4.6x﹣4.6x=55.2x﹣993.6﹣4.6x,
50.6x﹣993.6=0,
50.6x﹣993.6+993.6=993.6,
50.6x=993.6,
50.6x÷50.6=993.6÷50.6,
x=19.;
(55)122﹣x﹣19=(x﹣19)×5,
103﹣x=5x﹣95,
103﹣x+x=5x﹣95+x,
103+95=6x﹣95+95,
198÷6=6x÷6,
x=33;
(56)3.5x+2=4x﹣1,
3.5x+2﹣3.5x=4x﹣1﹣3.5x,
2+1=0.5x﹣1+1,
3÷0.5=0.5x÷0.5,
x=6
(57)=
3.5(X﹣16)=1.5X,
3.5X﹣56=1.5X
3.5X﹣56+56=1.5X+56
3.5X﹣1.5X=56
2X=56
X=28,
(58)X+(3X﹣16)÷25%=10(X+1)
X+(3X﹣16)×4=10X+10
X+3X×4﹣16×4=10X+10
13X﹣64=10X+10
13X﹣64+64=10X+10+64
13X=10X+74
13X﹣10X=10X+74﹣10X
3X=74
X=
(59) 75÷(x+10)=2,
75÷(x+10)×(x+10)=2×(x+10),
2x+20=75,
2x+20﹣20=75﹣20,
2x=55,
2x÷2=55÷2,
x=27.5;;
(60)5x﹣3×(28﹣x)=12+2x,
8x﹣84=12+2x,
8x﹣84+84=12+2x+84,
8x=96+2x,
8x﹣2x=96+2x﹣2x,
6x=96,
6x÷6=96÷6,
x=16
(61)6(x+1)=0.5(10x+16),
6x+6=5x+8,
6x+6﹣6=5x+8﹣6,
6x﹣5x=5x+2﹣5x,
x=2
(62)5(x+2)=4(x+9),
5x+10=4x+36,
5x﹣4x=36﹣10,
x=26;
(63)127.5÷(2x+3)=15,
127.5÷(2x+3)×(2x+3)=15×(2x+3),
15×(2x+3)=127.5,
15×(2x+3)÷15=127.5÷15,
2x+3=8.5,
2x+3﹣3=8.5﹣3,
2x=5.5,
2x÷2=5.5÷2,
x=2.75;
(64)3(x+2)=4(x+1),
3x+6=4x+4,
3x+6﹣3x=4x+4﹣3x,
x+4=6,
x+4﹣4=6﹣4,
x=2;
(65)8(x﹣1.5)=x+0.6,
8x﹣12=x+0.6,
8x﹣12+12=x+0.6+12,
8x=x+12.6,
8x﹣x=x+12.6﹣x,
7x=12.6,
7x÷7=12.6÷7,
x=1.8;
(66)7(x+6)﹣3x=4(2x+5),
7x+42﹣3x=8x+20,
4x+42=8x+20,
4x+42﹣4x=8x+20﹣4x,
4x+20=42,
4x+20﹣20=42﹣20,
4x=22,
4x÷4=22÷4,
x=5.5;
(67)4x﹣2(5.5﹣x)=3.5x﹣8,
4x﹣11+2x=3.5x﹣8,
6x﹣11=3.5x﹣8,
6x﹣11+11=3.5x﹣8+11,
3.5x+3=6x,
3.5x+3﹣3.5x=6x﹣3.5x,
2.5x=3,
2.5x÷2.5=3÷2.5,
x=1.2
(68)2.8x=19.32﹣6.4x,
2.8x+6.4x=19.32﹣6.4x+6.4x,
9.2x=19.32,
9.2x÷9.2=19.32÷9.2,
x=2.1;
(69)5(y﹣4)﹣7(7﹣y)﹣9=12﹣3(9﹣y),
5y﹣20﹣49+7y﹣9=12﹣27+3y,
12y﹣78=3y﹣15,
12y﹣78+78=3y﹣15+78,
12y﹣3y=3y+63﹣3y,
9y=63,
9y÷9=63÷9,
y=7
(70)35(x﹣2)﹣15(5x﹣6)=22x﹣63﹣21(3x﹣4),
35x﹣70﹣75x+90=22x﹣63﹣63x+84,
35x﹣75x﹣22x+63x=﹣63+84﹣90+70,
x=1
(71)2.6x=51.6﹣3.4x,
2.6x+3.4x=51.6﹣3.4x+3.4x,
6x=51.6,
6x÷6=51.6÷6,
x=8.6;
(72)3(4x﹣2)﹣2(3x+3)=9﹣8x,
6x﹣12=9﹣8x,
6x﹣12+8x=9﹣8x+8x,
14x﹣12=9,
14x﹣12+12=9+12,
14x=21,
14x÷14=21÷14,
x=1.5;
(73)20+4x=6x﹣24,
20+4x﹣4x=6x﹣24﹣4x,
2x﹣24=20,
2x﹣24+24=20+24,
2x=44,
2x÷2=44÷2,
x=22;
(74)5(x﹣1)=x+1,
5x﹣5=x+1,
5x﹣5﹣x=x+1﹣x,
4x﹣5=1,
4x﹣5+5=1+5,
4x=6,
4x÷4=6÷4,
x=1.5;
(75)3(3x﹣2)=10﹣0.5(x﹣3.5),
9x﹣6=11.75﹣0.5x,
9x﹣6+0.5x=11.75﹣0.5x+0.5x,
9.5x﹣6=11.75,
9.5x﹣6+6=11.75+6,
9.5x=17.75,
9.5x÷9.5=17.75÷9.5,
x=;
(76)0.4(x﹣0.2)+1.5=0.7x﹣0.38,
0.4x+1.42=0.7x﹣0.38,
0.4x+1.42﹣0.4x=0.7x﹣0.38﹣0.4x,
0.3x﹣0.38=1.42,
0.3x﹣0.38+0.38=1.42+0.38,
0.3x=1.8,
0.3x÷0.3=1.8÷0.3,
x=6;
(77)(0.6x+420)÷(x+20)=3,
(0.6x+420)÷(x+20)×(x+20)=3×(x+20),
3(x+20)=0.6x+420,
3x+60=0.6x+420,
3x+60﹣0.6x=0.6x+420﹣0.6x,
2.4x+60=420,
2.4x+60﹣60=420﹣60,
2.4x=360,
2.4x÷2.4=360÷2.4,
x=150;
(78)35(2﹣x)+15(6﹣5x)=22x+7+21(4﹣3x),
160﹣110x=91﹣41x,
160﹣110x+110x=91﹣41x+110x,
69x+91=160,
69x+91﹣91=160﹣91,
69x=69,
69x÷69=69÷69,
x=1
(79)5(3x﹣4)﹣2(x﹣1)=5(2x﹣1)
15x﹣20﹣2x+2=10x﹣5,
13x﹣18=10x﹣5,
13x﹣18﹣10x=10x﹣5﹣10x,
3x﹣18=﹣5,
3x﹣18+18=﹣5+18,
3x=13,
3x÷3=13÷3,
x=;
(80) x=4.9+x,
x﹣x=4.9+x﹣x,
x=4.9,
x×=4.9×,
x=10.5;
(81)3x+5×=2x+×,
3x+=2x+,
3x+﹣=2x+﹣,
3x=2x,
3x﹣2x=2x﹣2x,
x=0;
(82)X÷3.2=(18﹣x)÷5,
X÷3.2=(18﹣x)×,
X÷3.2×3.2=(18﹣x)×0.2×3.2,
X=11.52﹣0.64X,
X+0.64X=11.52﹣0.64X+0.64X,
1.64X=11.52,
1.64X÷1.64=11.52÷1.64,
X=7;
(83)4(4x﹣6)=5(3x+1),
16x﹣24=15x+5,
16x﹣24﹣15x=15x+5﹣15x,
x﹣24+24=5+24,
x=29
(84)10X=3(2X+17)+45,
10X=6X+51+45,
10X=6X+96,
10X﹣6X=6X+96﹣6X,
4X÷4=96÷4,
X=24;
(85)5.7(X﹣0.2)=5.1(X+0.6)+4,
5.7X﹣1.14=5.1X+3.06+4,
5.7X﹣1.14=5.1X+7.06,
5.7X﹣1.14﹣5.1X=5.1X+7.06﹣5.1X,
0.6X﹣1.14+1.14=7.06+1.14,
0.6X÷0.6=8.2÷0.6,
X=13
(86)(3x+4)+x=7(x﹣5)
4x+4=7x﹣35
4x+4﹣4x=7x﹣35﹣4x
3x﹣35=4
3x﹣35+35=4+35
3x=39
3x÷3=39÷3
x=13
(87)(9+21)x=66x÷60﹣40﹣440,
30x=1.1x﹣480,
30x﹣1.1x=1.1x﹣480﹣1.1x,
28.9x÷28.9=﹣480÷28.9,
x=﹣16
(88)x﹣2.5=(x﹣1.8)×2
x﹣2.5=2x﹣3.6
x﹣2.5﹣x+3.6=2x﹣3.6﹣x+3.6
x=1.1
(89)12+(x﹣12)×+x=x
12+0.2x﹣2.4+0.5x=x
0.7x+9.6=x
x﹣0.7x=9.6
0.3x=9.6
x=32
(90)3(X﹣3)+4(3X﹣2)=7(2﹣X),
3X﹣9+12X﹣8=14﹣7X,
15X﹣17=14﹣7X,
15X﹣17+7X=14﹣7X+7X,
22X﹣17+17=14+17,
22X÷22=31÷22,
X=1;
(91)﹣=﹣2,
18X﹣12﹣6X﹣9=6X+4﹣24,
12X﹣21=6X﹣20,
12X﹣21+21=6X﹣20+21,
12X﹣6X=6X+1﹣6X,
6X÷6=1÷6,
X=