yes, so note that AOB and BOC add up to AOC.

AOB + BOC = AOC

sub in the values given in the question to obtain

3x + 4 + 8x - 28 = 108

simple one-variable equation, x = 12.

and AOB is 3x + 4, so that's 3(12) + 4 = **40 **is your answer

hey, that makes cents