Dana wants to make two types of dog treats. she has 10 cups of peanut butter and 12 cups of flour. her dog bone treat recipe uses 3 cups of peanut butter and 2 cups of flour to make one tray. a tray of her oatmeal dog treat recipe uses 1 cup of peanut butter and 4 cups of flour. she plans to sell trays of dog treats at the town festival and charge $6 for a tray of dog bone treats and $7 for a tray of oatmeal treats. dana wants to maximize her income from selling the dog treats. when writing constraints for the problem, what is the most reasonable definition for the variables x and y?