Respostas

2013-08-11T18:33:57-03:00
Lucio=x
Bianca=y
x+y=15
2x=3y

x=15-y
substitui 
2x=3y
2(15-y)=3y
30-2y=3y
3y+2y=-30
5y=-30
y=-30/5
y=-6 (-1)
y=6

x+y=15
x+6=15
x=15-6
x=9
3 4 3
2013-08-11T18:37:09-03:00
L+b=15
2l=3b

l=15-b
substitui
2l=3b
2(15-b)=3b
30-2b=3b
3b+2b=-30
5b=-30
b=-30/5
b=-6 (-1)
b=6

L+b=15
l+6=15
l=15-6
l=9

2 3 2