If $$(54\sqrt{2}x^3 + 24\sqrt{3}y^3)\div (\sqrt{18}x + \sqrt{12}y) = Ax^2 + by^2 + Cxy$$, then what is the value of $$A^2 - (B^2 + C^2)?$$

A

12

B

-36

C

-24

D

24