Answer:
Correct choice is D
Explanation:
First second - 5 feet,
second second 5+7=12 feet,
third second 12+7=19 feet, i.e.
This rule represents the arithmetic sequence, where

You actually have to find
that can be calculated using formula:

In your case,

Then the sum of first 15 terms of the arithmetic sequence is the distance Ms. Waara traveled.
The sum of n terms of the arithmetic sequence is

that in your case takes look
