XYZ is an electronic manufacturing company which plans to improve the production of its products. There are four products incorporated in the production plan which are ASN-OI, ASN-02, ASN-03, and ASN-04. The planning process is a semi-annual planning (planning for six months). The demand data for each month, the production and storage costs, and the initial and final stock levels for every product are listed in the following table, Demand (units) Month Production cost (S/unit) Storage cost (S/unit/month) Initial stock (units) 10 Final stock (units) 0.4 Product ASN-01 1500 ASN-02 1300 ASN-O32200 ASN-04 1400 20 25 3000 800 1500 1600 2000 800 2900 1500 4000 1000 1800 1000 2000 1100 1200 1100 2500 900 2100 1200 0.5 0.3 10 10 IS 0.3 10 Also, there are additional costs for the increase or decrease in the production level; for an increase of production, there is a cost of $i per unit of increase, while there is only $0.50 per unit for the production decrease The company would like to establish the production plan that minimizes the sum of costs incurred through changes of the production level production and storage costs. Formulate the LP model for the problem using the compact form