Answer:
a = 93°, b = 120°, c = 150°
Step-by-step explanation:
b + 36 = 78 × 2 => b + 36 = 156 => b = 120°
87 × 2 - b = the minor arc between a and 78
=> 174 - 120 = 54
54 + b + 36 + c = 360
=> 54 + 120 + 36 + c = 360
=> c = 150°
(c + 36) ÷ 2 = a
=> (150 + 36) ÷ 2 = a
=> a = 93°
