What do the entries in the matrix 3A+B represent?

(E) Each week, Bill orders four types of coffee for each of three coffee shops. The amounts ordered, in pounds, are summarized below. Downtown Shop: 100 of Arabica, 150 of French Roast, 200 of Hazelnut, 75 of Breakfast Blend Train Station Shop: 50 of Arabica, 100 of French Roast, 150 of Hazelnut, 150 of Breakfast Blend Mall Shop: 200 of Arabica, 250 of French Roast, 300 of Hazelnut, 100 of Breakfast Blend 100 150 200 75 3A + B = 3 50 100 150 150 200 250 300 100 + 80 120 160 60 45 90 135 135 250 312.50 375 125 300 450 600 225 150 300 450 450 600 750 900 300 80 120 160 60 45 90 135 135 250 312.50 375 125 380 570 760 285 3A + B = 195 390 585 585 850 1062.50 1275 425