Define “Critical path”, “Slack time”, “Resource Levelling” and “Dummy activity”

Define “Critical path”, “Slack time”, “Resource Levelling” and “Dummy activity” with reference to PERT and CPM.
An architect has been awarded a contract to prepare plans for an urban renewal project. The job consists of the following activities and their estimated value. Draw a critical path arrow diagram for this project, indicate the critical path and calculate the total slack and free slack for each activity.