17(2-3y)-5(12-y)=8(1+7y),5(x-4)-7(7-x)-9=12-3(9-x)
问题描述:
17(2-3y)-5(12-y)=8(1+7y),5(x-4)-7(7-x)-9=12-3(9-x)
答
34-51y-60+5y=8+56y
-34=102y
y=-1/3
5x-20-49+7x-9=12-27+3x
9x=63
x=7