please answer all step by step

Question 4 1. Cable metal company Ltd. produces a special type of cable for industrial wiring and stores them in warehouses in Accra, Kumasi, and Takoradi. These warehouses supply cables to retail markets in Tama, Tarkwa, Nkwakwa and Bogoso. The following table shows the shipping costs per ton, supply and demand To (cost, in GH 00) From Tema Tarkwa Nkwakwa Bogoso Supply Accra 50 75 30 45 12 Kumasi 65 80 40 60 17 3 11 Takoradi Demand 40 10 70 10 50 10 55 10 a) Describe the decision variables for this transportation problem. AP(4 Marks) b) Develop a network graph showing all costs and decision variables. EV(8 Marks) c) Formulate the mathematical model that will be used to solve the problem on a computer CR(8 Marks)