I need help with these questions:

2. Danagger Coal is considering a strip mining project in Pennsylvania. The project will require an initial cash investment in 2016, generate cash revenues in 2017, and require land reclamation expenditures in 2018. Pre-tax cash flows, tax payments (or refunds) and after-tax cash flows associated with the project are shown in the table below.

Although Danagger faces a 35% corporate tax rate, Danagger's taxes in the years 2016- 18 are less than 35% of its pre-tax cash flows in those years because Danagger is able to take percentage depletion allowances to reduce its 2017 tax payments.

a. Danagger evaluates projects by discounting after-tax cash flows at its cost of capital r, r > 0. For what values of r should Danagger should invest in the project?

b. Taxes are zero-sum wealth transfers between Danagger Coal and the federal government. From that perspective, the federal government is just another stakeholder in Danagger Coal. For what values of r do the pre-tax cash flows have a positive net present value?

c. What effect does the tax system have on the economic efficiency of Danagger Coal's investment decisions?