To find the average rate of change in a interval

We use the following formula:

Applying this to our interval

We have the following rate of change:

We have an average rate of change equals to 6.
That expression would be 6n-3, where n is the number in question.
The nine in 79,401 is In the thousands place
Since Jessica has 40 cents, and one gum ball costs 8 cents, you need to divide 40/8 = 5. The answer is 5 gum balls