Answer
$\frac{x-2}{x+2}$
Work Step by Step
Since both expressions have common denominators, you can simply combine their numerators.
$\frac{x^2-4x}{x^2-x-6}-\frac{x-6}{x^2-x-6}$
$\frac{x^2-5x+6}{x^2-x-6}$
$\frac{(x-2)(x-3)}{(x+2)(x-3)}$
$\frac{x-2}{x+2}$