A couple will retire in 50 years; they plan to spend about $24,000 a year (in current dollars) in retirement, which should last about 25 years. They believe that they can earn a real interest rate of 7% on retirement savings. If they make annual payments into a savings plan, how much will they need to save each year? Assume the first payment comes in 1 year. How would the answer to part (a) change if the couple also realize that in 20 years they will need to spend $54,000 on their childs college education?