Solve please.

A simple network consisting of four activities has the following network diagram: The cost/time relationships for the activities are shown in the table below: For example, if completed in 5 weeks, activity A would require $85,000, and if completed in 10 weeks, it would require $70,000. a. What is the minimum cost of completing this project in 20 weeks? b. If the desired completion date is 33 weeks and the profit markup is 20 percent above cost, what should be the bid price for this project