Question 2: (20 pts) A firm has 5 workers and 6 workstations and the managers want to assign the workers to workstations to minimize cost. The extra workstation will be operated by a part-time worker. The cost of the part-time worker is fixed and does not affect the decision. The cost of assigning each employee to each workstation is given in the following table: Machine Employee 1 A B C D E F 9 13 6 14 14 7 2345 2 20 11 16 9 18 5 17 14 3 1 7 9 16 1 15 18 4 9 5 10 8 14 12 15 1 Because of skills of workers, worker 2 cannot be assigned to machine B, and worker 4 has to be assigned to machine D. Formulate a linear programming model to solve this problem. Define your decision variables properly.