Long-term investment decision, payback method Personal Finance Problem Bill Williams has the opportunity to invest in project A that costs $8,900 today and promises to pay annual cash flows of $2,100, $2,500, $2,500, $2,100 and $1,800 over the next 5 years. Or, Bill can invest $8,900 in project B that promises to pay annual cash flows of $ 1,300, $ 1,300, $ 1,300, $3,700 and $3,900 over the next 5 years