4. USX Steel expects to faces the following demand during the next 4 months: 300 tons; 150 tons: 250 tons; and 100 tons, respectively. At the beginning of month 1, USX has 12 workers. During any month, a worker at USX can produce up to 20 tons of steel. Each worker is paid $6500 per month. At the start of each month, a worker can be hired at the cost of $4300 or fired at the cost of $5400. Demand may be backlogged at a cost of $110 per month per ton of steel; and the cost of holding a ton of steel in inventory for one month is $120. The raw material used to produce a ton of steel costs $510. All demand must be met at the end of month 4. Formulate an LP to help USX Steel minimize the total costs during the next 4 months. A. Define the decision Variables B. Write out the objective function C. Write out all the constraints