Ok, use the sum of triangle theorm all angles of the triangle has a sum of 180 degrees. B is 90 degrees because it labeled it self ABC the A angle seems by the degree to be at the top of the triangle and there needs to be a 90 degree angle in a right triangle. Now if you add 90 + 28 you get 118 degrees subtract that from the sum of all the angles ( 180 degrees), and get 62 degrees as angle C. Angle A is 28 degrees, angle B is 90 degrees, angle C is 62 degrees.