Respostas

2013-11-06T22:52:49-02:00
10y-5(1+y)=3(2y-2)-20
10y-5-5y=6y-6-20
10y-5y-6y= -20-6+5
-y=-21
y=21
2013-11-07T01:35:41-02:00
10y - 5 (1 + y) = 3 (2y - 2) - 20
10y - 5 - 5y = 6y - 6 - 20
10y - 5y - 6y = - 6 - 20 + 5
-y = - 21
Multiplicando ambos por (- 1) fica:
y = 21