Question

The graph below shows the amount of money left in the school’s desk fund, f, after d desks have been purchased.

For each new desk that is purchased, by how much does the amount of money left in the school’s desk fund decrease?

Answer 1

The amount left in the fund decreases by $110 for each desk purchased.
We suspect that each new desk probably costs $110.

Answer 2

$110 is the decrease in the school desk's fund for each new desk is purchased.

Explanation:

We have to calculate the amount of money left in the school's desk fund when a new desk is purchased.

From the given link we find two points (2, 480) and (5, 150), and the decrease in fund when a desk is purchased will be denoted as

Decrease in school's desk fund after a new purchase = Change in y coordinates of the points / difference in x-coordinates

= (480-150)/(5-2) = 330/3 = $110

Answer is $110.