Howard is about 193.9 yards from the top of the reservoir.
This is a trigonometry problem. If you draw a picture of the situation, you will see that you have an adjacent side and need to know the hypotenuse.
That makes it a cosine problem:
cos(64) = 85/x
x = 85/cos(64)
x = 193.9
He is about 193.9 yards from the top of the reservoir.