怎么看这个房屋的草图尺寸求求好心人教教我

3(x+y)-4(x-y)4
(x+y)/2+(x-y)/61
令ax+y,bx-y
3a-4b4 (1)
a/2+b/61
则3a+b6 (2)
(2)-(1)
5b2
b2/5
a(6-b)/328/15

x+y28/15
x-y2/5
相加
2x34/15
x17/15
y28/15-x11/15