Hi there,
The answer is she can buy 28 small cans. She can also buy 40 medium cans with the same. I gonna explain how I did that way you know if you be ask for explanation here we go. I did 200 divided by 5 = 40 small cans and you also do the same by the medium 200 divided by 5 = 40 small cans. you can also add and add that will take long time.
I hope I did easy way to make you understand.