Shelby Company produces three products: product X, product Y, and product Z. Data concerning the three products follow (per unit): Demand for the company's products is very strong, with far more orders each month than the company can produce with the available raw materials. The same material is used in each product. The material costs $3 per pound, with a maximum of 4,000 pounds available each month. Compute contribution margin per pound of materials used. Which orders would you advise the company to accept first, those for product X, for product Y, or for product Z? Which orders second? Third