An animal breeder can buy four types of food for vietnamese pot-bellied pigs. each case of brand a contains 35 units of fiber, 30 units of protein, and 30 units of fat. each case of brand b contains 70 units of fiber, 20 units of protein, and 20 units of fat. each case of brand c contains 105 units of fiber, 10 units of protein, and 30 units of fat. each case of brand d contains 140 units of fiber, 40 units of protein, and 20 units of fat. how many cases of each should the breeder mix to obtain a food that provides 1785 units of fiber, 330 units of protein, and 510 units of fat?