In need help with this algorithm question

Consider the following jobs and service times. The goal is to schedule the jobs in such a way to minimize the total time in the system that they spent both for waiting and for its service; such a schedule is optimal. 1. Design a recursive greedy algorithm to minimize the total amount of time spent in the system. 2. Design an iterative greedy algorithm for the same problem. 3. What is the optimal solution of the above problem? Give a sequence of job and its minimum total time