Respostas

2014-04-27T21:50:12-03:00
X⇒caneta
y⇒lapiseira
x+y= 10,80
2x+y=12,60

x=10,80-y

2(10,80-y)+y=12,60
21,60-2y+y=12,60
-2y+y=12,60-21,60
-y=-9 .(-1)
y=9

x+9=10,80
x=10,80-9
x=1,8
2 5 2