Answer:
There would need to be nine.
Explanation:
4 x 5 = 20 5 cars is to little of a umber
4 x 7 = 28 close
4 x 8 = 32 8 cars carry 32 people but there is one student left out of that car so they would need an extra car.
The the goes "Well.... flop. I'm alone"
:D
So nine cars.
*eliza*