A larger and more modern main post office is to be constructed at a new location in$$ Davis, California. Growing suburbs caused a shift in the population density from where it was $40$ years$$ ago, when the current facility was built. Annette$$ Werk, the$$ postmaster, asked her assistants to draw a grid map of the seven points where mail is picked up and delivered in bulk. The coordinates and trips per day to and from the seven mail source points and the current main post$$ office, M$,$ are shown in the following table. M will continue to act as a mail source point after relocation.