John and Sam were hungry so they ordered an extra-large pizza that was pre-sliced into 12 pieces. John ate 3 slices while Sam ate twice the amount that John ate. How many slices of pizza were left? Give me reasons, before answering the question
Sam had twice the amount of John so Sam ate 3 * 2 = 6 slices. Together, they ate 3 + 6 = 9 slices. 1 pizza has 12 slices. 9 slices were eaten so 12 - 9 = 3 slices left. So the final answer is 3.