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 B D E 13 14 2 16 18 3 17 14 3 1 7 9 4 16 15 4 14 15 1 6 14 9 20 F 7 5 11 9 1 8 18 12 9 1 5 10 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