Respostas

2013-12-07T20:15:29-02:00
X/y =3/4
x+y =28

x+y = 28
y=28-x

substituindo,
x/28-x =3/4
4x= 3(28-x)
4x=84-3x
7x=84
x=12
y=28-x
y=16
2 5 2