A Company in Brisbane has to fulfill orders for 120 tonnes per week of concrete required in Adelaide, and 180 tonnes per week of concrete required in Sydney. This company has two factories, each of which can produce 150 tonnes per week. No concrete block in excess of market demand should be shipped and delivery cost per tonne from each factory to Adelaide and to Sydney is shown in the following table. Em--- \"m Formulate the model for determining the lowest cost shipping plan to fill the above orders