If a new car is valued at $13,200 and 6 years later it is valued at $3000, then what is the average rate of change of its value during those six years?

I'm not in college so take what I say with a grain of salt but to figure that out first I found the range of 13,200 and 3,000 or basically subtracted 3,000 from 13,200 to get 10,200 so it's value went down 10,200 dollars worth of value in six years, next I divided 10,200 by six because it was six years. To get a rate of change of 1,700 dollars worth of value each year. So the answer is an average rate of 1,700 dollars during those six years or 1.28%