A national retail chain receives credit card payments from four regions of the country (West, Midwest, East, and South).The average daily payments from each area are given in the Table.This company's management must decide where customers should mail their payments.An annual interest rate of 18% can be earned on cash received.The company is considering setting up payment centers in four cities: San Francisco, St. Louis, Philadelphia, and Tampa.The average number of days that elapse between the time a payment check is mailed and the time the check is credited to one of the company's accounts also are given in Table.The annual cost of operating a payment center is $100,000.

Moreover, each payment center that is opened could handle at most $270,000 per day in payments.All of the customers in each region must send all of their payments to a single payment center.This company wants to determine the payment center configuration that minimizes the sum of annual lost interest and center operating costs.\

I am looking for the decision variables and the objective function. Also the constraints used for this problem so I can set up the excel?

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