There are some muffins in a box. The muffins can be put into plates of 3 or 6 with no muffins leftover. When the muffins are put into plates of 7, there are short of 6 muffins on the last plate. If there are more than 30 muffins but less than 50 muffins, how many muffins are there in the box?
If muffins can be put into plates of 3 or 6 with no muffins leftover, the number of muffins is a multiple of 6 as 6 is a multiple of 3.

Multiples of 6 that are greater than 30 but less than 50: 30, 36, 42, 48

Multiples of 7 that are greater than 30 but less than 50: 35, 42, 49
Multiples of 7 (- 6) that are greater than 30 but less than 50: 29, 36, 43

Common number = 36

Number of muffins = 36

Answer(s): 36