Answer:
∠COS = 30°
Step-by-step explanation:
∠BPO = 120° + x
∠COS = x
Alternate Interior/Exterior is congruent if two parallel lines are intersected by a transverse.
∠BPO = ∠COP
∠COP = 120° + x
∠COP + ∠COS = 180°
120° + x + x = 180°
120° + 2x = 180°
2x = 60°
x = 30°
