Question

The floor of a canyon has an elevation of −14.5 feet. Erosion causes the elevation to change by −1.5 feet per year. How many years will it take for the canyon floor to have an elevation of −31 feet?

Answer 1

11 Years,

The difference between the levels is 16.5,
And feet/year is -1.5,
So 16.5/-1.5 is -11, but since we cannot have a negative number we take the absolute value for an answer of 10.

Answer 2

The answer would be 11 years.

Explanation:

This is how I would do it:

1. take 31 and subtract 14.5 from it. Will get you 16.5

2. take 16.5 and divide it by 1.5.

3. You will get 11 as an answer.