Answer:
He needs to move 15 feet.
Explanation:
If you are ten feet underneath the water then you have to move 10 feet to reach the surface.
After you reach the surface you are at 0ft above or below the water. You must move 5 more feet to reach the point 5 feet above the water.
You add the ten feet to reach the surface and the five feet to reach the end point and you will get an answer of 15 feet.
