An anticipated purchase of equipment for $520,000, with a useful life of 8 years and no residual value, is expected to yield the following annual net incomes and net cash flows: year net income net cash flow 1 $60,000 $120,000 2 50,000 110,000 3 50,000 110,000 4 40,000 100,000 5 40,000 80,000 6 40,000 80,000 7 40,000 60,000 8 40,000 60,000 what is the cash payback period? a. 6 years b. 5 years c. 3 years d. 4 years