#### Answer

$-\frac{3\sqrt 2+9}{7}$

#### Work Step by Step

Multiply the numerator and denominator by the conjugate and then simplify the radicals:
$\frac{3}{\sqrt 2-3}\times\frac{(\sqrt 2+3)}{(\sqrt 2+3)}=\frac{3\sqrt 2+9}{\sqrt 4+3\sqrt 2-3\sqrt 2-9}=-\frac{3\sqrt 2+9}{7}$