Setup system and solve by graphing: Certain laboratory animals must have at least 30 g of protein and at least 20 g of fat per feeding period. These nutrients come from food A, which cost 18 cents per unit and supplies 2 g of protein and 4 g of fat, and food B, with 6 g of protein, 2g of fat, and costs 12 cents per unit. Food B is bought under a long-term contract requiring that at least 2 units of B be used per serving. How much of each food must be bought to produce the minimum cost per serving? What is the minimum cost per serving?