Question

what is the value of x? and how did you get the answer

Answer 1

OA = OB = OC  [radii]  ⇒ ΔAOB and ΔCOB are isosceles  ⇒
∠ABO = ∠OAB = 30°
∠CBO = ∠OCB = 50°
x = ∠ABO + ∠CBO = 30 + 50 = 80°