need a, b, and c. please

An investment project has annual cash inflows of $2,800,$3,700,$5,100, and $4,300, for the next four years, respectively. The discount rate is 9 percent. a. What is the discounted payback period for these cash flows if the initial cost is $5,200 ? (Do not round intermediate calculations and round your answer to 2 decimal places, e.g., 32.16.) b. What is the discounted payback period for these cash flows if the initial cost is $6,400 ? (Do not round intermediate calculations and round your answer to 2 decimal places, e.g., 32.16.) c. What is the discounted payback period for these cash flows if the initial cost is $10,400 ? (Do not round intermediate calculations and round your answer to 2 decimal places, e.g., 32.16.)