Adding and subtracting integers

Question

If a divers elevation is at negative 30 and she dives down 12 more feet,what’s her elevation after the dive?

Answer 1

So the diver is currently at -30, and then she dives down another 12. Let's try to visualize it:

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V-30

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---here

When you are subtracting from a negative, you can think of it as you are adding even more negative to the amount. Like if you owe your friend 5 dollars and then borrow another five, you now owe your friend 10 dollars.

-5 - 5 = -10, or -5 + (-5) → -(5 + 5)= -10

so here we have -30 - 12 → -(30 + 12) = -(42) → -42

We started at negative 30 feet, then we added 12 more negative feet, to the final depth of negative 42 feet.