Question 910672
A + B + C = 78
A = B + 5 
C = 3B - 2
(B+5) + B + (3B-2) = 78
5B + 3 = 78
5B = 75
B = 15
If B is 15, then C is 43, and A is 20.
15 + 43 + 20 = 78