You can break off the labeled angles into a triangle, all the angles in a triangle add up to 180. If you draw a straight line down you will get a right angle at the end of your trapezoid. 180-90 = 90. So now you have x + (x-38) = 90. 2x -38 = 90 2x = 128 x = 64 (x-38) = 26
