Please explain answers

The following table is a transportation matrix showing the cost (\$) per unit of shipping from Plant i to Distributor j. The objective is to minimize shipping costs while meeting the demand placed by each Distributor. There is no shipment between Plant 2 and Distributor 3. Let xij= number units shipped from Plant i to Distributor j Solve the transportation problem and use the result to fill the boxes below. All answers are equally weighted. a) At optimal solution: x11=x21=x31=x12=x22=x32=x13=x23=x33= Minimum Cost =$