A dietician is planning a snack package of fruit and nuts. Each ounce of fruit will supply zero units of protein, 3 units of carbohydrates, and 2 units of fat, and will contain 40 calories. Each ounce of nuts will supply 4 units of protein, 2 units of carbohydrates and 4 units of fat, and will contain 50 calories. Every package must provide at least 8 units of protein, at least 18 carbohydrates, and no more than 18 units of fat. Find the number of ounces of fruit and number of ounces of nuts that will meet the requirment with the least number of calories. What is the least number of calories? z=?x+?y