Complete question:
Given the following diagram, if and mCOF = 150°, then mBOC = _____.
150°
90°
45°
30°
I attached a possible diagram that I found in a similar problem.
Using the diagram, I can see that ∠COF is supplementary to ∠BOC. This means that the sum of their angles is equal to 180°.
m∠COF + m∠BOC = 180°
m∠COF = 150°
m∠BOC = 180° - 150° = 30° Choice D.
