Question

a 12-pounded bag of dog food costs $12.36. a 15-pounded bag of cat food cost $15.30. which is a better deal???

Answer 1

Each pound of the dog food costs  $1.03 .
Each pound of the cat food costs  $1.02 .

If you own a dog, then the dog food is the better deal.

If you own a cat, then the cat food is the better deal.

You would not want to feed your pet on food formulated for
a different species of animal, just to save a few pennies.

For that matter, I'll bet you could save a TON of money by
feeding your whole family dog food or cat food three times
a day !