To be honest, I'm just doing this part because I looked up this answer and only saw your guy's equation, so if anyone is looking this up, (the question below), here is the answer.
Given
\qquad m \angle AOCm∠AOCm, angle, A, O, C is a straight angle.
\qquad m \angle AOB = 8x + 51^\circm∠AOB=8x+51
∘
m, angle, A, O, B, equals, 8, x, plus, 51, degrees
\qquad m \angle BOC = 6x - 25^\circm∠BOC=6x−25
∘
m, angle, B, O, C, equals, 6, x, minus, 25, degrees
Find m\angle AOBm∠AOBm, angle, A, O, B:
For that specific equation, it would be 139
