Answer
$\frac{x - 4}{(x + 4)(x + 3)}$
Work Step by Step
$x^{2} - 7x + 12$ can be factored to (x - 4)(x - 3)
$x^{2} + 8x + 16$ can be factored to (x + 4) (x + 4)
$x^{2} - 9$ can be factored to (x + 3)(x - 3)
The problem can be simplified to:
$(\frac{(x - 4)(x - 3)}{(x + 4)(x + 4)})$$(\frac{x + 4}{(x + 3)(x - 3)})$ = $\frac{x - 4}{(x + 4)(x + 3)}$