Please explain each step of the solution for better understanding. Thank you.

Consider a one period Reverse Logistic problem where a truck with a capacity of 20 units need to drop off customer demand (di) and pickup appropriate amount of backhaul items (ei). Any backhaul item not picked incurs a penalty of ai. Table below gives for each customer i, the demand (di), available backhaul items (ei), and penalty (ai). Assuming that transportation cost is insignificant compared to penalty cost, (a) Use an appropriate Heuristic Method discussed in the class (or propose your own heuristic!) to determine the route (sequence in which to visit the customers). (b) Given the route obtained in part (a), determine the amount Zi of backhaul items to pick up at each customer location so as to minimize total penalty cost. (describe the logic you used to determine the Zi values at each customer