Okay, So what you need to do first is divide 228 by 30 we get 7.6 so let’s just say 6 Buses because there is no such thing as half students lol. Then you would times 6 by 30 which is 180. We would have 6 vans which hold 8 students 6*8 is 48. Then we could add 180 +48 which is 228.
To sum it up
6 Vans
6 Buses
Hope you have a wonderful day~ <3