A poll was taken of 100 students at a commuter campus to find out how they got to campus. The results were as follows:

28 said they drove alone.
37 rode in a carpool.
27 rode public transportation.
8 used both carpools and public transportation.
8 used both a carpool and sometimes their own cars.
4 used buses as well as their own cars.
3 used all three methods.

How many used none of the above-mentioned means of transportation?

1 answer

28+37+27-8-8-4+3 = 75

so, 100-75 = 25 used none of the 3 methods