If there are 108 students, and the vans can hold up to 5 students, then you would need 22 vans.
If you were to divide 108 by 5, then you would get 21.3 . That 3 is the remaining children, therefore, to fit them in the trip, you would need another van, hence, 22 vans. The van that is not full would have 3 children in it.
