$-8\mathrm{.}20$ The following table gives the map coordinates and the shipping loads for a set of cillies that we wish to connect through a central hub.

$\backslash$table$[[$CITY$,$MAP COORDINATE $(x,n),$SHIPPING LOAD$],[$A$,(5,10),5],[$s$,(6,8),10.],[$C$,(4,9),15.],[$D$,(9,5),5^{-}$