Answer
$$\frac{\left(x-1\right)\left(x+2\right)}{\left(x+1\right)^2}$$
Work Step by Step
Trying to find like factors in the numerator and the denominator, we obtain:
$$\frac{\left(x^2+3x-4\right)\left(x^2-3x-10\right)}{\left(x^2-4x-5\right)\left(x^2+5x+4\right)} \\ \frac{\left(x-1\right)\left(x+4\right)\left(x+2\right)\left(x-5\right)}{\left(x+1\right)^2\left(x-5\right)\left(x+4\right)} \\ \frac{\left(x-1\right)\left(x+2\right)}{\left(x+1\right)^2}$$
