Quadrilateral ABCD​ is inscribed in this circle. What is the measure of angle C? Enter your answer in the box. ° A quadrilateral inscribed in a circle. The vertices of quadrilateral lie on the edge of the circle and are labeled as A, B, C, D. The interior angle A is labeled as left parenthesis 2 x plus 38 right parenthesis degrees. The angle B is labeled as 3 x degrees. The angle D is labeled as left parenthesis x plus 20 right parenthesis degrees.