Angle ACB is an inscribed angle of circle P. Find x if angle ACB measures x° and arc ACB measures (x + 45) °.

According to the theorem of circles, angle ACB is equal to 1/2 of the explementary angle of angle APB. The explementary angle then is 360 - (x+45) or 315 - x where x is angle ACB. Hence x = 0.5 * (315-x). x is equal to 105 degrees.