Please show the working out, so I understand the concept. Thank you

A factory has three departments A, B and C that have an excess of pallets over and above their needs and four departments, D, E, F and G that require pallets. The excesses and requirements are shown in the fioollowing table: Department Excess pallets Pallets required A B C D E F G 75 90 60 45 45 60 45 The times involved in moving the pallets from the departments with excesses to those needing pallets are shown in the following table: Time, minutes From D E F A 12 25 13 21 B 9 23 14 18 23 15 12 16 What is the optimum distribution plan to minimize total delivery time? What is the total minimum time involved in distributing the excess pallets