Mary is 50 years old. After she retires in 20 years (at t=20), Mary would like an annual income of $80,000.00. Just to be safe that she does not run out of funds before she dies, she would like this yearly income for a period of 25 years after retirement (t=21 to t=45). Mary has already saved $100,000.00, which she intends to invest for her retirement needs. She also plans to save x% of her annual income of $100,000.00 till she retires. Mary is willing to take risks for the next 10 years (t=1 to 1=10). But after she wants to invest in a safe investment till she retires (t=11 to t=20), earning 5% in the safe mutual fund. She will continue with the safe fund after her retirement as well. (HINT: this information tells us the appropriate discount rates before and after retirement). What fraction (x%) of her yearly income will she need to save till she retires, so that she can meet her investment needs for retirement? (For now do not worry about nominal vs. real analysis).