The orange top cab company has a taxi waiting a each of four cabstands in Evanston, Illinois. Four customers have called and requested service. The ditances, in miles, from the waiting taxis to the customers are given in the following table. Find the optimal assignment of taxis to customers so as to minimize total driving distances to the customers.
Cab site A B C D
Stand 1 7 3 4 8
Stand 2 5 4 6 5
Stand 3 6 7 9 6
Stand 4 8 6 7 4