I just need help on D

Given the following network diagram for a project (activity times are in days): a) Determine Earliest Start time (ES), Earliest Finish time (EF), Latest Start time (LS), Latest Finish time (LF), and Slack Time for each activity. ES Slack Activity 1-2 1-3 1-4 2-5 2-6 3-7 4-7 5-8 6-8 7-8 b) Identify the Critical Path(s). c) What is the expected project duration? d) If the project duration must be reduced by 3 days, which activities will most likely be affected