Respostas

2013-10-16T01:13:36-03:00
X+y = 20
5x - 3y = 4

x = 20 - y

5.(20-y) - 3y = 4
100 -5y -3y = 4
100 -8y = 4
-8y = 4 - 100
-8y = -96 .(-1)
y = 96/8
y = 12

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

3 4 3