Bob, Tom, Sally, and Jerry had dinner at their favorite pizzeria. They decide to share 2 pizzas. Bob ate half of a pizza on his own. Tom ate one-third of a pizza. Sally wasn't very hungry and only ate one-sixth of a pizza, and Jerry ate a quarter of a pizza. If each pizza is cut into 12 slices, how many slices were left over? Let's think first. Chain of thought:
Each pizza is 12 slices. Bob at 12 slices / 2 = 6 slices. Tom ate one third, or 12 slices / 3 = 4 slices. Sally ate one sixth, or 12 slices / 6 = 2 slices. Jerry ate one quarter, or 12 slices / 4 = 3 slices. In total, they ate 6 slices + 4 slices + 2 slices + 3 slices = 15 slices. So they were left with 12 slices per pizza * 2 pizzas - 15 slices = 24 slices - 15 slices = 9 slices.
Therefore, the answer is 9.