Answer:

15 feet below sea level

Step-by-step explanation:

so think of it this way the submarine was already 21 feet below sea level..if it moves up it gets closer to sea level which means we have to subtract..so 21-6=15

Answer:

The Submarine is 15 feet below the sea level

Step-by-step explanation:

Hope it helps

Pa brainliest po pag tama