16. What is the present value of an annuity of $20,000 received at the beginning of each year for 10 years, with a return of 8% annually? 17. What is the present value of an annuity of $50,000 received every six months for 5 years, with a return of 9% compounded semiannually? 18. What is the present value of an annuity of $10,000 received every three months for 15 years, with a return of 12% compounded quarterly? 19. What is the present value of an annuity of $5,000 received monthly of 3 years, with a return of 6% compounded monthly? 20. Hillary is injured by a bus called "The Straight Talking Express". She won a lawsuit and will receive $5,000 per month, at the beginning of each month, for the next 20 years. How much must "The Straight Talking Express" deposit into an account earning 6%, compounded monthly, to satisfy this judgement?