Question

A submarine at 20 feet below the sea level suddenly moves up 5 feet. The submarine is below the sea level.

• A. 15 feet
• B. –15 feet
• C. –25 feet
• D. 25 feet

Answer 1

The correct option is A 15 feet

20 feet below the sea level $\to –20$ feet
Moves up 5 feet $\to +5$ feet

Thus, the submarine is now at $(–20+(+5\left)\right)$ feet.

Since the signs are different, we,

• Write the absolute values of the integers.
• Subtract them.
• Put the original sign of the larger number to the difference.

$\therefore –20+(+5):$

• $|–20|=20,|5|=5$
• $20–5=15$
• $–20+(+5)=–15$

–15 feet means 15 feet below the sea level.
Thus, the submarine is 15 feet below the sea level.