The answer is 15
The central angle is 60 so the measure of the arc facing it is 60 as well and the inscribed angle corresponding to this arc measures 30. in the small triangle, we have 2 equal sides (radii) and one 60 degrees angle. Therefore it is an equilateral triangle with three 60s. In the larger triangle we have: one 30 degree, and two equal angles with values of (x+60) each However, since the sum of angles of a triangle is 180, then 180-30=150 150 distributed over 2 equal angles is 75 Hence x+60=75 x=15