you are planning to save for retirement over the next 15 years. to do this, you will invest $1,100 a month in a stock account and $500 a month in a bond account. the return on the stock account is expected to be 7 percent, and the bond account will pay 4 percent. when you retire, you will combine your money into an account with a 5 percent return. how much can you withdraw each month during retirement assuming a 20-year withdrawal period?