a-d is one problem! please help with this

7. Environmental Recycling, Inc. must clean up a large automobile tire dump under a state environmental cleanup contract. The tasks, duration (weeks), costs and predecessor relationships are shown in the table below. a. Draw the project network. b. Identify the critical path(s) c. What is the total project-completion time and total cost? d. What is the total project-completion time and lowest-cost solution if the state wants to complete the project 3 weeks early