If CB is a diameter, the arc BKAC is a semicircle and has a degree measure of 180. If the measure of angle BCK is 20 and it is an inscribed angle, then the measure of the arc it intercepts is twice that. So arc BK measures 40 degrees. That means that arc KA has a measure that is found by subtracting arc AC and arc BK from 180. 180 - 40 - 110 = 30. If that arc is 30 and the angle that intercepts it is inscribed, then the angle measure is half the measure of the arc. So the angle is 15°
