Answer:
∠AOB = 139°
Step-by-step explanation:
The 2 angles form a straight angle and sum to 180°, that is
∠AOB + ∠BOC = 180 ← substitute values
8x + 51 + 6x - 25 = 180, that is
14x + 26 = 180 ( subtract 26 from both sides )
14x = 154 ( divide both sides by 14 )
x = 11
Hence
∠AOB = 8x + 51 = (8 × 11) + 51 = 88 + 51 = 139°
