Question 2: XYZ Company provide cleaning services to Montreal area businesses through its 12 retail centers. Every Sunday, company does an inventory audit to identify weakly needs for cleaning materials (comes in boxes as a set). While some of the retail centers will have shortage (needs to be replenished), some retail centers carry surplus from the previous week. If a retail center needs replenishment of an inventory, company first tries to supply the needs from another retail center if there is any surplus. Otherwise, the item will be satisfied from the distribution center. Below network graph shows the links between retail stores and the cost of transporting a box of item between each stores. The table below provides the demand for the following week and the current availability at each store. Finally, in the same table, cost of transporting a box from distribution center to retail store is given. Based on the given information, write a mathematical model to help XYZ to replenish all its retail centers to the desired level with the minimum transportation cost