Long-term investment decision, payback method Personal Finance Problem Bill Williams has the opportunity to invest in project A that costs $ 7300 today and promises to pay $ 2 200, $ 2400, $ 2400, $ 1900 and $ 1900 over the next 5 years.  Or, Bill can invest $ 7300 in project B that promises to pay $ 1300, $ 1300, $ 1300, $ 3700 and $ 4,000 over the next 5 years