Question

A swimmer dives 10 feet below the surface of a lake

Answer 1

Answer:

She must swim 10 feet before she reaches the surface; from level -10 to level 0 (Equation: $-10+10=0$)

Step-by-step explanation:

Based on the information provided, you can assume that the surface of the lake is at level 0.

 You know that the swimmer dives 10 feet below the surface; this is the level -10 .

This means that she must swim 10 feet from the level -10  to the level 0 in order to reach the surface of the lake.

Therefore, to find how far she must swim before she reaches the surface, it is necessary to add levels -10 and +10 to get the level 0. This can be represented with the following equation:

$-10+10=0$