Assuming you begin investing $$15,000$ per year beginning this year and continue investing this same exact amount each year for the next $40$ years $(40$ total payments$)$ with a guaranteed and consistent $5$ percent ROI, no more and no less, answer the following questions:

a$.$ How much of your own money will you have invested after $40$ years?

b$.$ How much will your retirement account be worth at the end of $40$ years?

c$.$ Using the answer you calculated for Problem $5$ above, what would the equivalent worth of your retirement savings be in today$$s dollars?