Answer:
-525 feet
Step-by-step explanation:
If a submarine was below sea level, that would mean that it would be at an elevation of negative feet down, so if it's 800 feet below sea level, it's elevation would be -800.
to ascend means to rise, so the submarine would be moving +275 feet (going higher, closer to sea level)
so you can make out this equation: -800 + 275
this would equal: -525
