I am having difficulty creating equations from problems such as this one...

In 2008, Mariana paid $14 500 for a used 2005 van. She has been tracking the selling price of the van as time has passed to decide how long to keep the van before replacing it. The data she has collected is shown in the following table:

Age (in years)

Age in years : 3 Selling price: 14 500

4 years - 11 600

5 yrs - 8700

6 yrs - 6800

7 yrs - 4300

8 yrs - 3500

Selling Price ($)

a. Determine the equation of the exponential regression function that models the depreciation of the van.

b. What was the initial selling price of the van in 2005?

c. What is the annual depreciation rate of the van?