4x-2(3-x)=12 7(x-2)=28 4x-3(20-x)=6x-7(9-x) 4(2y+3)=8(1-y)-5(y-2) 5(x-4)-7(7x-9)=12-3(9-x)

题目

4x-2(3-x)=12 7(x-2)=28 4x-3(20-x)=6x-7(9-x) 4(2y+3)=8(1-y)-5(y-2) 5(x-4)-7(7x-9)=12-3(9-x)

答案

4x-2(3-x)=12
4x-6+2x=12
6x=18
x=3
7(x-2)=28
x-2=4
x=6
4x-3(20-x)=6x-7(9-x)
4x-60+3x=6x-63+7x
6x=3
x=1/2
4(2y+3)=8(1-y)-5(y-2)
8y+12=8-8y-5y+10
21y=6
y=2/7
5(x-4)-7(7x-9)=12-3(9-x)
5x-20-49x+63=12-27+3x
47x=58
x=58/47