7x+6(x-y)=130.1
7y-2(x-y)=10 .2
1式-2式得
7(x-y)+4(x-y)=120
11(x-y)=120
x-y=120/11你做错了是错了7x+6(x-y)=130..............17y-2(x-y)=10 ...............21式-2式得7(x-y)+8(x-y)=12015(x-y)=120x-y=8这下做对了