If A = 7, G = 5 + A, A = 1 + 3B, then A + G + B =?

Option A

A = 7
12 = 5 + 7 A
A = 1 + 6(3 B)

Hence,
1 A = 7
1 G = 1
1 B = 2

Therefore,
1 A + 11 G + 1 B = 20.