Respostas

2013-12-10T12:49:42-02:00
x= motos 
y= carros

x+y=20          -2
2x+4y=56

-2x-2y=-40
2x+4y=56

2y=16
y=16/2
y=8

x+y=20
x+8=20
x=20-8
x=12

Logo são 12 motos e 8 carros.
2 3 2
2013-12-10T12:50:01-02:00
X= motos
y= carros

2x+4y= 56
x+y=20

2x+4y=56
-2x-2y=-40

2y= 16
y= 8

x+8=20
x=12 motos
1 5 1