Respostas

2013-10-13T17:34:44-03:00
4a - 12 - 12 - 3a  = 0
4a - 3a =  12 + 12
a = 24

2013-10-13T17:34:57-03:00
4(A- 3) - 3( 4 + A) = 0
4A -12 - 12 - 3A = 0
A -24 = 0
A = 24