please solved and explain steps

Roger Ginde is developing a program in supply chain management certification for managers. Ginde has listed a number of activities that must be completed before a training program of this nature could be conducted. The activities, immediate predecessors, and times appear in the accompanying table: This exercise contains only parts b,c, and d. b) The critical activities for the leadership training program development project are This exercise contains only parts b,c, and d. b) The critical activities for the leadership training program development project are (1) c) The project length for the leadership training program development project = days. d) Slack time for each of the activities is