question in chemical engineering

Example 2 . The sales figure for two car dealers during January showed that Dealer A sold 5 deluxe, 3 premium and 4 standard cars, while Dealer B sold 7 dluxe, 2 premium and 3 standard cars. Total sales over the 2-month period of January-February revealed that Dealer A sold 8 deluxe, 7 premium and 6 standard cars. In the same 2-month period, Dealer B sold 10 deluxe, 5 premium and 7 standard cars. Write 2 x 3 matrices summarizing sales data for January and the 2-month period for each dealer. Hence find the sales in February for each dealer