please answer with explanation

Problem 5 You have just received a windfall from an investment you made in a friend's business. She will be paying you $15,000 at the end of this year, $20,000 at the end of next year, and $25,000 at the end of the year after that (i.e., in three years from today). The interest rate is 3.5% per year and compounding takes places annually. a. What is the present value of your windfall? b. What is the future value of your windfall in three years from now (i.e., on the date of the last payment)