Question

Alina and Joe are both thinking of the same positive number. Alina tells Joe that her number is a factor of 9, while he tells her that it is a factor of 12. If the number is not 1, what is it?

Answer 1

9 and 12 have a factor of 3

Answer 2

It is 3, given that
$3 \times 3 = 9$
and
$3 \times 4 = 12$