There are four muffins on each plate there are zero plates of lemon muffins how many lemon muffins are there

There are no lemon muffins. You know that there are 4 muffins because it was stated in the problem. It is also stated that there are 0 lemon muffins. So you can conclude that none of the four muffins that are on the plate are lemon muffins, therefore being another flavor.