Answer:
Oliver is 8 feet above the surface of the water.
There is a school of fish 10 feet below the surface.
A ledge with some seashells is 18 feet below the surface.
There is a shipwreck 32 feet below the surface.
Part A:
Assuming that all given depths are from surface level.
Now Oliver will go down 8 feet to reach the surface of water, then again 18 feet below that to get to the seashells.
So, total he will go down
feet
Part B:
feet
The shipwreck is 22 feet more deeper than the school of fish when measured from surface level.