Calculating ES EF LS and LF times in Project

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Calculate the ES, EF, LS, and LF times and the slack for each activity in the figure below and identify the critical path for the project. Can the project be completed in 40 weeks? Assume that Activity A actually finished at 3 weeks, Activity B actually finished at 12 weeks, and Activity C actually finished at 13 weeks. Recalculate the expected project completion time. Which activities would you focus on in order to get the project back on schedule?