find a, if a=b=c Please

Answer:
∠a = 60
Step-by-step explanation:
∠a = ∠b = ∠c
180 = ∠a + ∠b + ∠c
180 = ∠a + ∠a + ∠a
180 = ∠a (3) ( divide both sides by 3)
∠a = 60