Final answer:
To find the fraction of the whole casserole that Kayleigh packed into each container, subtract the amount she ate from 1 and then divide by 3.
Step-by-step explanation:
To find the fraction of the whole casserole that Kayleigh packed into each container, we need to divide the amount packed by the total amount. Let's say Kayleigh ate x of the casserole. Then, the fraction she packed into each container would be 1 - x divided by 3. This is because she packed the remaining casserole, which is 1 - x, into 3 identical containers. Therefore, the fraction of the whole casserole that Kayleigh packed into each container is (1 - x)/3.