A company is considering opening warehouses in 4 cities: seattle, LA, chicago, and Atlanta. Each warehouse can ship 100 units/wk. the weekly fixed cost of keeping each warehouse open is $800 NY, $1K LA, $600 chicago, $450 atlanta. Region 1 of country requires 80 units/wk. region 2 requires 70units/wk, region 3 requires 40units/wk. the costs of sending 1 unit from a warehouse to a region are given in the following table:

Fr/To: Region1 Region2 Region3

Seattle 20 40 50

LA 48 25 26

Chicago 26 35 19

Atlanta 24 50 35

The company also needs to satisfy the following conditions 1)if Chicago warehouse is opened, then LA warehouse must be opened

2)at most 2 warehouses can be opened

3) if seattle warehouse is opened, then LA warehouse cannot be opened

FORMULATE AN INTEGER-PROGRAMMING MODEL FOR THIS PROBLEM