You are in charge of buying office supplies for your business. Your workers use red and black pens. Red pens cost $5 per box and black pens cost $3 per box. You need at least 10 boxes of pens. You want no more than 7 boxes of black pens and no more than 6 boxes of red pens. You want to minimize the cost to your business.

The objective function for this situation is C = 5x + 3y. What (x, y) pair minimizes cost?
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(6, 7)

(0, 7)

(3, 7)

(6, 4)

Your vet has placed your pet on a diet. the diet is to contain at least 12 mg of fat and at least 14 mg of protein per serving. these requirements are to be obtained from two food sources. source a contains 2 mg of fat and 2 mg of protein per serving. source b contains 1 mg of fat and 3 mg of protein per serving. if source a sells for $1.28 per serving and source b sells for $1.12 per serving, how many servings of each type should be purchased to satisfy the requirements at minimal cost?