A diver is at -18 m. She swims up 18 m. Where is she now?

Step by step

The question

Question: A diver is at −18 m.

She swims up 18 m.

Where is she now?

1 Write it as a sum

We start at −18.

Swims up means up: add 18.

Sea level is 0.

Below it is negative.

2 Work it out

Start at −18.

Go up 18.

Careful!

We start at −18, not at 18.

Keep the minus sign.

We land on 0 m.

So the answer is 0 m: Right at sea level.

3 Check

Let's check: go back.

0 minus 18 is −18, where we started.

So the answer is right!

Let's look back.

First: write it as a sum.

Then: work it out.

Last: check.