36 students each went to one revision class.
1/6 of the students went to the physics revision class.
2/9 of the students went to the biology revision class.
All of the other students went to the chemistry revision class.
How many students went to the chemistry revision class?
(Sorry, I'm not really sure about this problem. But If I were you I would probably add 1/6 + 2/9 to see how many student in total did not go to the chemistry revision class. I'm terrible at math, sorry I couldn't help that much.)
