Can someone help me with this question?

Year O 1 2 3 Cash Flow -$7,600 2,000 6,000 4,400 a. What is the profitability index for the cash flows if the relevant discount rate is 9 percent? b. What is the profitability index for the cash flows if the relevant discount rate is 17 percent? c. What is the profitability Index for the cash flows if the relevant discount rate is 24 percent