Need help solving a-c. Please and thank you.

A mining company is considering a new project. Because the mine has received a permit, the project would be legal; but it would cause significant harm to a nearby river. The firm could spend an additional $10 million at Year 0 to mitigate the environmental problem, but it would not be required to do so. Developing tin- mine (without mitigation) would cost $60 million, and the expected cash inflows would be $20 million per year for 5 years. If the firm does invest in mitigation, the annual inflows would be $21 million. The risk-adjusted WACC is 12%. a. Calculate the NPV and IRR with and without mitigation. b. How should the environmental effects be dealt with when this project is evaluates c. Should this project be undertaken? If so, should the firm do the mitigation