Each one of a given customers needs to be assigned to one production plant and one recycling plant. There are p potential sites for production plants~ with a xed cost )3} of Operating such a plant in location j U=1....,p). Likewise. there are 4; potential sites for recycling plants' with xed costs g; for each location It (1%],qu Let of}; denote the cost of assigning customer 3' to production plant j and recycling plant it. (This cost may include transportation between i and j, between i and k, as well as between j and k, and possiny other cost elements). Formulate the problem as an integer programming