In the diagram, POR is a circle with center O. ∠QPR = 50°, ∠PQO = 30° and ∠ORP = m. Find m.

A.
20^{o} 
B.
25^{o} 
C.
30^{o} 
D.
50^{o}
Correct Answer: Option A
Explanation
< QOR = 50° x 2 = 100°
Reflex < QOR = 360° – 100° = 260°
(therefore) 30° + 50° + 260° + m = (4 – 2) x 180°
340° + m = 360°
m = 360° – 340° = 20°