Numerical Ability

Question.no.116
What wil come in place of both the question marks (?) in the following equation ?
(X^2/108)=(16/X)..

1)18
2)16
3)12
4)24
5)none

Note : X=? and X^2=X power 2


Answer..

(X^3)=108*16
(X^3)=1728
(12^3)=1728
X=12

3)12