please explain and show all steps/work

12. Your brother is 25 and recently graduated college and has started working full time. He currently has no money. He wants to retire at age 45 as a millionaire. You recommend that he invest monthly in a stock mutual fund that would earn him 9%, compounded monthly. How much will your brother have to invest each month to achieve his goal? What would the answer be if he retired at age 70 instead