#### Answer

$6\sqrt {3}-6\sqrt {2}$

#### Work Step by Step

$3\sqrt {108}-2\sqrt {18}-3\sqrt {48}$ Factor.
$3\sqrt {36}\sqrt {3}-2\sqrt {9}\sqrt {2}-3\sqrt {16}\sqrt {3}$ Simplify.
$18\sqrt {3}-6\sqrt {2}-12\sqrt {3}$ Combine like radicals.
$6\sqrt {3}-6\sqrt {2}$