A retail chain has $6$stores in a region supplied from $3$ supply sources. Trucks have a capacity of $25,000$ units and cost $$(1000+261)$per load plus $$(100-43\mathrm{.}5)$per delivery. The cost of holding one unit in inventory at retail for a year is $$1\mathrm{.}5.$ The managers will set upmilk runs from suppliers to retail stores. Assume that all trucks travel full. Suppliers are considering whether to run a milk run to $2$ stores or $3$stores on each truck. Determine a demand threshold in selection of the two options given