A rancher has a six-year old pony that weighs about 180 pounds. A pony of this age and size needs about 6.2 Mcal of digestible energy, 260 grams of protein, and 9,700 IU of vitamin A in her daily diet. EquineHealth and PonyEssentials are two popular brands of horse feed. One serving of the EquineHealth feed costs $10.50 and provides 1.5 Mcal, 52 grams of protein, and 1,800 IU of vitamin A. One serving of the PonyEssentials feed costs $12 and provides 1.8 Mcal, 58 grams of protein, and 2,200 IU of vitamin A. If the rancher were to blend the two feed products to make horse feed for his pony, how much of each brand should he use each week to minimize the cost? Explain and discuss your answer.