What is the difference between marginal revenue and total revenue ?

Our uncle has $300,000 invested at 7.5%, and he now wants to retire. he wants to withdraw $35,000 at the end of each year, starting at the end of this year. he also wants to have $25,000 left to give you when he ceases to withdraw funds from the account. for how many years can he make the $35,000 withdrawals and still have $25,000 left in the end? a. 14.21b. 14.96c. 15.71d. 16.49e. 17.32