Answer:
550 ft below sea level
Explanation:
Let's assume a vertical axis pointing upwards. This means that the submarine, being 800 feet away from the horizon in the opposite direction with respect to the axis, will have a negative height of
If it ascends 250 feets, it gains altitude, so the new height is
Note: this problem heavily depends on the coordinate system you adopt. In fact, I may have chosen an axes whose origin is set at the initial position of the submarine (which would have become the
pointing upwards, and the new position would have been
feet.
[RevyBreeze]