Perhaps there is another arc measure on the circle that might offer a hint. I know that inscribed angles are half of the intercepted arc measure. I also know that the central angle that intercepts the same arc is twice as big as that inscribed angle.Without seeing the problem, all we can do is offer possibilities. Try to ask the question again, but include some detail.
If an angle is inscribed in a circle, then the measure of the angle is equal to one-half the measure of its intercepted arc. I'm sure that another angle in your diagram has been given to you but you have not been able to see it. Go back to your circle and carefully look at the picture. Otherwise, more information is needed.
mathland