Can someone please tell me how to do this question? Or what steps I need to take with the work so I can understand how to do it?

A recent project nominated for consideration at your company has a four-year cash flow of $20,000; $25,000; $30,000; and $50,000. The cost of the project is $75,000.

1. If the required rate of return is 20%, conduct a discounted cash flow calculation to determine the NPV.

2. What is the benefit-cost ratio for the project?

3.Assuming the required rate of return remains 20%, what would the NPV of the above project be if the inflation rate was expected to be 4% in each of the next four years?