Answer
$\frac{x-3}{x-6}$
Work Step by Step
Use trial and error and the formula $a^2-b^2=(a+b)(a-b)$ to factor the numerator and denominator, and then divide.
The domain includes all real numbers except for $6$ and $-6$ because they make the original expression undefined.
$\frac{x^2+3x-18}{x^2-36}$
$\frac{(x+6)(x-3)}{(x+6)(x-6)}$
$\frac{x-3}{x-6}$
