Question

Carlos is having a bake sale, he begins with one tray of brownies. [cut into 15 pieces] and 18 cookies. He sells 1/3 of the brownies, and 1/6 of the cookies. He is then given a box of 12 tasty cakes to sell. He sells 3/4 of the box, how much of each food will he have left? What is the total percentage of items that he sold that day?