Supplementary angles add to 90°.. don't get confused with the 2 right angles in problem one because those =180°. Problem 2 has a right triangle in the middle which is 90°. Keep in mind the flat surface that the light bounces off is 180°. So you subtract the 90° you're given from the 180°. If the x's are equal, you can use that answer and simply divide by 2, for each x. X=45°
