13. Calculate the present value of the present value of $100 received 1, 2, ..., 10 years from today when annual compound interest rates are 0,5, 10, 15, 20%. Using the results, calculate the present value of annuity that pays $100 at the last day of every year for the next 10 years when annual compound interest rates are 0,5, 10, 15, 20%