Respostas

2014-04-03T10:08:19-03:00
A+b+c+d=15

a = 3

b  = 2 * 3 = 6

c = 1/3 * 3 = 1

Substituindo:

a+b+c+d=15 \\  \\ 3+6+1+d=15 \\  \\ \boxed{d=5}