13. A woman plans to retire in 40 years, and she expects to live for 40 years after that. She wants to spend $10,000 a month after she retires. To finance her retirement, she is going to invest monthly (with her first investment one month from now) over 40 years at 12.6%. After she retires, she will move her investment to a more liquid account earning 7.2% a year. Ignore taxes and transaction costs. How much does she have to save a month until her retirement? a. $89.22 c. $110.46 b. $103.49 d. $269.54