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

29

said they drove alone.

36

rode in a carpool.

36

rode public transportation.

6

used both carpools and public transportation.

4

used both a carpool and sometimes their own cars.

6

used buses as well as their own cars.

1

used all three methods.

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