A  Cell Phone company has three production plants each of which produces three different models of cell phone. The daily production capacity of each plant (in thousands) is as follows.

PlantsModel 1Model 2Model 3
Plant 1848
Plant 2663
Plant 31248

The total demand for Model 1, Model 2 and Model 3 are 3000 units, 1720 units and 2495 units. Moreover, the daily operating cost of plant 1 is £550, for plant 2 is £600 and for plant 3 is £600.How many days should each plant be operated in order to fill the total demand and minimize the total cost of production.