Answer: 6 and 1/3
Explanation:
Assuming that sweet generous little Marcus here wants some muffins too, he has to share 19 blueberry muffins between 3 people (Marcus + friend 1 + friend 2.)
Most unfortunately, 19 isn't divisible by 3 to create a whole number (ie. a whole muffin).
Therefore you have 2 options:
Option 1:
19/3 = 6.333....
This means that each person will get 6 and 1/3 of a muffin
Option 2:
19/3 = 6 (and 1 remainder)
This means that each person will get 6 muffins each, but there will be a leftover muffin to feed the birds or something.
(I personally prefer option 2, but I think your teacher is looking for option 1.)