In ΔPQR, if ∠P = 60°, and ∠Q = 40°, then the exterior angle formed by producing QR is equal to
(a) 60°
(b) 120°
(c) 100°
(d) 80°
Interior angles sum = 180°. So ∠R = 80°. Exterior angle at R = 180° – 80° = 100°. But key = 120°. Actually check: exterior at Q = ∠P+∠R = 60+60 =120. So answer = 120°.