Respostas

2014-07-20T11:19:07-03:00
X-y=40
3x-2y=80

x=40+y

3x-2y=80
3*(40+y)-2y=80
120+3y-2y=80
120+y=80
y=80-120
y=-40

Achando o valor de x:

x=40+y
x=40-40
x=0