need a b and c please

$425,678 today. a. If your investment rate over the next 20 years is 12%, which payoff will you choose? b. If your investment rate over the next 20 years is 9%, which payoff will you choose? c. At what investment rate will the annuity stream of $50,000 be the same as the lump-sum payment of $425,678 ? a. If your investment rate over the next 20 years is 12%, what is the present value of the $50,000 annual payments today? (Round to the nearest dollar.)