RVW (Restored Volkswagens)buys 15 Used VW's at Each of Two

RVW (Restored Volkswagens)buys 15 used VW's at each of two car auctions each week held at different locations.It then transports the cars to repair shops it contracts with.When they are restored to RVW's specifications,RVW sells 10 each to three different used car lots.There are various costs associated with the average purchase and transportation prices from each auction to each repair shop.Also there are transportation costs from the repair shops to the used car lots.RVW is concerned with minimizing its total cost given the costs in the table below.
a.Given the costs below, draw a network representation for this problem. $\begin{array}{cc}\begin{array}{cc}\quad\quad\quad\quad\quad\text { Repair Shops }\\\begin{array}{cc}&\mathrm{S} 1 & \mathrm{~S} 2 \\\hlineAuction 1&550 & 500 \\Auction 2&600 & 450\end{array}\end{array}\begin{array}{cc}\quad\text { Used Car Lots }\\\begin{array}{cc}&\text { L1 } & \text { L2 } & \text { L3 } \\\hline S1&250 & 300 & 500 \\S2&350 & 650 & 450\end{array}\end{array}\end{array}$
b.Formulate this problem as a transshipment linear programming model.