For MB distribution, costs C,, are as given in Table 6'8 (i = l'2'3'4' i = 1'2' ' ' ' '7) ' comparing with the original wholesaler-retailer shipping costs in Table 6.2,
there are no infeasible silpplng routes for wholesaler-retailer transportation (table 6.9). For transshipment-destination transportation, we introduce the following decision variables: