If you invest $18,000 today, how much will you have in each of the following cases? Enter all answers as positive amounts. a. In 7 years at 9 percent? (Round your final answer to 2 decimal places.) b. In 19 years at 8 percent? (Round your final answer to 2 decimal places.) c. In 16 years at 8 percent (compounded semiannually)? (Round your final answer to 2 decimal places.)