解方程組{4x+8(x+y)=480,4y+9(x+y)=480

解方程組{4x+8(x+y)=480,4y+9(x+y)=480

4x+8(x+y)=480
4y+9(x+y)=480
2式相减
x-y-(x+y)=0
-2y=0
y=0
x=40