Percent Math Problem!?! 10 Points to Fastest & Most Accurate Answer! You Buy a New Car for $22,500…….?

You buy a new car for $22,500. The value of the car decreases by 25% each year.

a. Write an exponential decay model giving the car's value V (in dollars) after t years.
b. What is the value of the car after 3 years?
c. Graph the model (if you could just tell me how that'd be awesome….)
d. In approximately how many years is the car worth $5300?

***EVEN if you can only help me with one PLEASE do that'd still be great. I am really stumped on ALL of this. 10 points as soon as I can to the best answer!

* 11 minutes ago
* – 4 days left to answer.

Additional Details
I don't have a working calculator!!! And PLEASE explain HOW you got those answers??

Suggestion:

a V = (.75)^t * ($22500)

b V = (.75)^3 (22500) = 9492.19

c just plot a few points and graph it
(0, 22500)
(1, 13875)
(2, 12565.25)
(3, 9492.19 )
(7, 3003.39)
(10, 1267.05)
(15, 300.68)

d 5300 = (.75)^t (22500)

.235556 = (.75)^t

ln(.235556) = ln[(.75)^t]

ln(.235556) = t*ln(.75)

t = ln(.235556) / ln ( .75)

t = 5.026

fyi: there are many online calculators you can use. Just google online calculator or use this one
http://www.math.com/students/calculators/source/scientific.htm