Fordco produces cars in Detroit and Dallas. The Detroit plant can produce up to 6500 cars, and the Dallas plant can produce up to 6000 cars. Producing a car costs $2000 in Detroit and $1800 in Dallas. Cars must be shipped to three cities. City 1 must receive 5000 cars, city 2 must receive 4000 cars, and city 3 must receive 3000 cars. The costs of shipping a car from each plant to each city are given in the file P05_57.xlsx. At most 2700 cars can be sent from a given plant to a given city. Determine how to minimize the cost of meeting all demands.