Would someone please outline the steps for this question, but without actually answering it?
A vet designs a special diet for a cat. This diet requires that the cat be allowed no more than 1500 calories, but at least 400 g protein. The vet can special-order the animal's food, but would prefer instead to mix to ready-made foods. (The question gives me two foods, with the calories, protein, and cost per tin listed.) List the constraints, and find a mixture which provides an adequate diet at the lowest costs.
I would like to understand the steps, which is why I have been vague with the details. Thanks in advance for your advice.