A café makes waffles and pancakes. Each waffle takes 3 minutes to cook, and each pancake takes 2 minutes to cook. The café has 30 minutes available for cooking each morning. The café must make a non-negative number of waffles and pancakes. Which system of inequalities best models the cooking time constraint and non-negative requirements on the number of waffles ( x ) and pancakes ( y ) the café can make?