#### Answer

$\frac{1}{x-3}$

#### Work Step by Step

To simplify, divide both the numerator and denominator by their greatest common factor.
Use the distributive property to find the GCF.
$\frac{3}{3x-9}=\frac{3}{3(x-3)}=\frac{3\div3}{3(x-3)\div3}=\frac{1}{x-3}$