The average of a certain car was $18,000 ten years ago. This year the average cost is

Question:

The average of a certain car was $18,000 ten years ago. This year the average cost is $30,000.
Calculate the average monthly inflation rate (fm) for this model.
Given the monthly rate, fm, what is the effective annual rate, f, of inflation for this model?
Estimate what these will sell for 10 years from now, expressed in today's dollars?