4. Three industrial sites are considered for locating manufacturing plants. The plants send their supplies to three customers. The supply at the plants, the demand at the customers, and the unit transportation cost from the plants to the customers are given in the following table.

Unit transportations cost ($)

~ 1 2 3 Supply Plant 1 10 15 12 1800 2 17 14 20 1400 3 15 10 11 1300 Demand 1200 1700 1600 In addition to the transportation costs, fixed costs are incurred at the rate of $12,000,

$11,000, and $12,000 for plants 1,2, and 3, respectively. Formulate the problem as an ILP and find the optimum solution.