Algebra
posted by Sue Jackson on .
A poll was taken of 100 students on how they got to campus. 33 drove alone, 35 rode in a carpool, 26 rode public transportation, 6 used both carpool and public transportation, 8 used both a carpool, 6 used buses as well as their own cars, 5 used all three methoda. How many are not using any of the treee?

assuming all you need is confirmation of the answer you obtained through your hard work,
21