Tomas works as an underwater photographer. He starts at a position that is 17 feet below sea level. He rises 8 feet, then descends 13 feet to take a photo of the coral reef. Enter and expression to find his position relative to sea level when he took the photo and evaluate the expression.

  -17 +8 -13 = -22   (22 ft below sea level)

Step-by-step explanation:

  -17 +8 -13 = -22

__

You can consider the problem to be represented by a number line with feet above sea level on the right, and feet below sea level on the left. The number 0 represents sea level.

Then 17 feet below sea level corresponds to -17 on the number line.

Rising 8 feet corresponds to adding 8 to the number on the number line.

Descending 13 feet corresponds to subtracting 13 from the number on the number line.

Together, these operations amount to ...

  -17 +8 -13

The ending position is -22 on the number line.

Tomas took the photo at 22 feet below sea level.