Can you explain HOW to calculate the Early Start, Early Finish, Late Start, and Late Finish times and the slack for each activity in the figure (see attached imagine)? What formulas should I use? How can I find the critical path for the project and can the project be completed in 40 weeks? Would it be best to use Excel to find these values?

What if Activity A actually finished at 3 weeks, Activity B actually finished at 12 weeks, and Activity C actually finished at 13 weeks? What would the project timeline be like then?

Activity B Activity E 2 10 5 7 Activity A Activity D Activity G 1 2 4 15 7 12 Activity H Activity C 8 Activity F 5 3 8 6 20