Hi, need help verifying answer to this question from manhattan cat exam.

If 72 cupcakes must be divided equally among the students in a certain class, how many students are in the class?

1) If the number of students is reduced by one-third, each student will receive 3 more cupcakes.
2) If the number of cupcakes is doubled, each student will receive 12 cupcakes.

I am getting (B) as my answer, as my equation for S1) is quadratic.... this right?