Question

A dolphin was swimming 9 feet below sea level. The number line shows the location of the dolphin. It then swam up 5 feet. Describe how to use the number line to find the new location of the dolphin. -10 -9 8 7 6 5 4 3 -2 -1 1 2 3 4 5 6 7 8 9 10 O

Answer 1

We know that a dolphin was swimming 9 feet below sea level, this can be represented with the number -9 because sea level represents zero level as the image below shows.

Then, the dolphin swam up 5 feet, which means we have to sum 5 to -9 which gives -4. The image below shows.

Notice that we had to jump 5 units up to find the new location of the dolphin, that's the way to do it.

Therefore, the new location is 4 feet below sea level.