Following table shows location information and volume of shipped quantities from a warehouse to several retail stores. Find the optimal location for the supply point using the center-of-gravity method. Show all calculations

\begin{tabular}{|l|r|r|r|} \hline RetailOutlet & X coordinate & Y coordinate & ShippedQuantity(tons) \\ \hline A & 20 & 5 & 1,800 \\ \hline B & 18 & 15 & 3,500 \\ \hline C & 3 & 16 & 2,600 \\ \hline D & 3 & 4 & 2,100 \\ \hline E & 10 & 20 & 4,000 \\ \hline \end{tabular}