Answer:
7
Explanation:
Notice that 28, 14, and 7 are multiples of 7.
Each box can contain only 1 type of item.
All boxes must have the same number of items.
Put 7 packages of notebook paper in 1 box.
Put 14 erasers in 2 boxes, 7 erasers per box.
Put 28 glue sticks in 4 boxes, 7 glue sticks per box.
Answer: 7