c) Based on a), suppose refining facility 1 manager signs a contract that if it is open, the chemical company must guarantee a minimum total sale of 600. Please write new constraints reflecting this contract (no need to repeat the same constraints to a)).

A chemical company owns four factories that manufacture a certain chemical in raw form. The compan would like to get in the business of refining the chemical. It is interested in building refining facilities, and it has identified three possible sites. Table 1 contains variable costs, fixed costs, weekly capacities for the three possible refining facility sites, and weekly production amounts for each factory. The variable costs are in dollars per week and include transportation costs. The fixed costs are in dollars per year. The production amounts and capacities are in tons per week. N Refining sites Factory 1 3 production 1 25 15 1000 Factory 2 15 20 1000 locations 3 20 15 25 500 25 15 15 500 Fixed cost 500.000 500.000 500,000 Capacity 1500 1500 1500 Table 1. Cost, capacity, and production information for the chemical company.