What is the measure of the angle at which the light ray hits the water? What is the measure of the angle at which the light ray is reflected from the water?

From the figure, we have three angles on the straight line.
x , x , and 90
Sum of angles on a straight line = 180
x + x + 90 = 180
2x + 9 = 180
2x = 180 - 90
2x = 90
x = 90/2
x = 45
The measure of the angle at which the ray hit the water = 45
The measure of the angle at which the ray reflected from the water = 45