I need help on #3!!!

Answer:
[tex]\frac{{x}^{2} - 9}{{x}^{2} - 16} [/tex]
Step-by-step explanation:
[tex][\frac{(x - 3)(2x + 1)}{(x - 4)(x + 5)}][\frac{(x + 3)(x + 5)}{(x + 4)(2x + 1)}] = \frac{(x - 3)(x + 3)}{(x - 4)(x + 4)} = \frac{{x}^{2} - 9}{{x}^{2} - 16}[/tex]
In order to figure this out, you have to factor every single trinomial in the denominators and numerators. By doing this, you will arrive at your answer alot swifter.
I am joyous to assist you anytime.