this is business analysis problem, please help with problem b) (I have included the equation)

proposed plants are as follows: The company's long-range planning group developed forecasts of the anticipated annual demand at the distribution centers as follows: The shipping cost per unit from each plant to each distribution center is as follows: What is the optimal cost? What is the optimal set of plants to open? (b) Using equation 13.1, find a second-best solution. What is the optimal set of plants to open? What is the increase in cost versus the best solution from part (a)? $ proposed plants are as follows: The company's long-range planning group developed forecasts of the anticipated annual demand at the distribution centers as follows: The shipping cost per unit from each plant to each distribution center is as follows: What is the optimal cost? What is the optimal set of plants to open? (b) Using equation 13.1, find a second-best solution. What is the optimal set of plants to open? What is the increase in cost versus the best solution from part (a)? $