#### Answer

$15$

#### Work Step by Step

Using $(a+b)(a-b)=a^2-b^2$, or the special product of the sum and difference of like terms, the given expression, $
(3\sqrt{2}-\sqrt{3})(3\sqrt{2}+\sqrt{3})
,$ simplifies to
\begin{array}{l}\require{cancel}
(3\sqrt{2})^2-(\sqrt{3})^2
\\\\=
9(2)-3
\\\\=
18-3
\\\\=
15
.\end{array}