3. A transportation problem assume there are 4 warehouses containing Personal protective equipment, commonly referred to as "PPE," supplies being used at 6 hospitals. Given the supplies available at each warehouse and the demand at each hospital, and the unit costs of transporting them (all known values), construct a model to determine how much gets transported from each warehouse to each hospital that minimizes the total transportation costs. To do this you need to make up your notation for all variables and parameters. Plug in values of the parameters of the model and solve it to find how much is shipped from each warehouse to each hospital. What condition has to be satisfied for your model to be feasible