You like to make a hamburger with a mixture of pork and beef, but the exact ratio isn’t important. What does matter is that you have exactly $42 to spend on the meat. You also know that you need at least 10 pounds of meat. You are trying to figure out your options while standing in front of the butcher’s counter and notice that pork costs $3.50 per pound, while the beef costs $4.50 per pound. How many pounds of pork should you buy?