Two years ago Abilia purchased a $13,000 car; she paid $2,500 down and borrowed the rest. She

Question:

Two years ago Abilia purchased a $13,000 car; she paid $2,500 down and borrowed the rest. She took a fixed rate 60-month installment loan at a stated rate of 7.0% per year. Interest rates have fallen during the last two years and she can refinance her car by borrowing the amount she still owes on the car at a new fixed rate of 4% per year for 3 years. Should Abilia refinance her loan?
How much will she save per month for the remainder of the loan life if she decides to refinance?