y-x=x-4 y-x=40-y
问题描述:
y-x=x-4 y-x=40-y
答
y-x=x-4
y-2x=4 2y-4x=8
y-x=40-y
2y-x=40
3x=32
x=32/3
y=4+2x=4+(64/3)=76/3不对y-x=x-4y-2x=-42y-4x=-8y-x=40-y2y-x=402y-x=402y-4x=-83x=48x=16y=4+2x=4+32=36