Answer:
a) 115°
b) 30°
Step-by-step explanation:
∠D = ∠SPB = 35°
RS // QP ∠C = ∠D = 35°
∠RQP + ∠RSP = 180° ∠b = 180°-35°-35°-80° = 30°
∠a = 180° - 30° - 35° = 115°
check: ∠a = 1/2 (arc QP + arc PS) = 1/2 (160°+70°) = 115°
