How do I approach this problem? I am particularly confused about the IRR subquestion.

X402 Math for Management: Problem Set 9 1. A project your company is contemplating is expected to generate the following cash flows over the next 4 years: -550.000 1 2 +260.000 3 +380.000 Calculate the: (a) Payback period (b) Internal Rate of Return (0) Net Present Value (assume 5% discount rate)