I believe that the angles measures are assumed in degrees, and I also believe that the interval for the unknown "x" is from 0 to 360 degrees. Then from sin(x) = cos(y), x + y = 90 degrees. Therefore, x - 15 + (30 + 2x) = 90 3x + 15 = 90 3x = 90-15 = 75 x == 25 degrees. ANSWER