can someone help with these two problem

Your aunt offers you a choice of $21,000 in 25 years or $640 today. At a discount rate of 15 percent, how much is your aunt's offer of $21,000 worth today? (Enter your answer as a positive number rounded to 2 decimal places.) .-2. Which offer should you choose? $21,000 in 25 years $640 today If you invest $12,250 today, how much will you have in each of the following cases? Enter all answers as positive amounts. a. In 8 years at 6 percent? (Round your final answer to 2 decimal places.) b. In 16 years at 7 percent? (Round your final answer to 2 decimal places.) c. In 15 years at 14 percent (compounded semiannually)? (Round your final answer to 2 decimal places.)