4(x+y)=80 5(x-y)=80
问题描述：
4(x+y)=80 5(x-y)=80
过程,
答
4(x+y)=80 5(x-y)=80
x+y=80/4=20
x-y=80/5=16
(x+y)+(x-y)=2x=20+16=36
x=18
y=20-x20-18=2
x=18y=2