Southeastern is debating whether to close some of these warehouses to avoid paying the fixed $3600 for each of them. Update the problem to see if they could close some facilities and save money while still meeting the volume needed. What is the new total distribution cost (fixed warehouse costs plus variable distribution cost) for the optimal configuration (with some closed warehouses that won't be incurring the $3600 no more)? Hint: include the in-use constraint