A nutritionist working for a space agency must meet certain minimum nutritional requirements and yet keep the weight of the food at a minimum. He is considering a combination of two foods, which are packaged in tubes. Each tube of food A contains 4 units of protein, 2 units of carbohydrates, and 2 units of fat and weighs 3 kilograms. Each tube of food B contains 3 units of protein, 6 units of carbohydrates, and 1 unit of fat and weighs 2 kilograms. The requirement calls for 42 units of protein, 48 units of carbohydrates, and 16 units of fat. How many tubes of each food should be supplied to the astronauts