A Company in Adelaide has to fulfill orders for 100 tonnes per week of concrete required in Melbourne, and 140 tonnes per week of concrete required in Sydney. This company has two factories, each of which can produce 120 tonnes per week. No concrete block in excess of market demand should be shipped and delivery cost per tonne from each factory to Melbourne and to Sydney is shown in the following table. Svdnev Factory 1 $150 $210 120 tonnes Factory 2 $160 $220 120 tonnes 100 tonnes 140 tonnes Formulate the model for determining the lowest cost shipping plan to fill the above orders