A recent college graduate begins a savings plan at age 27 by investing $400 at the end

Question:

A recent college graduate begins a savings plan at age 27 by investing $400 at the end of each month in an account that earns 7.5%, compounded monthly.

(a) If this plan is followed for 10 years, how much should the monthly contributions be for the next 28 years in order to be able to withdraw $10,000 at the end of each month from the account for the next 25 years?

(b) What is the total amount contributed?