Answer
$\dfrac{2x-8}{x^2+x-2}$
Work Step by Step
The expressions are not similar. Make them similar by using the LCD, which is $(x+8)(x-1)$, to have:
$\\=\frac{4(x-1)}{(x+2)(x-1)} -\frac{2(x+2)}{(x-1)(x+2)}
\\=\frac{4x-4}{(x+2)(x-1)}-\frac{2x+4}{(x+2)(x-1)}
\\=\frac{4x-4-2x-4}{(x+2)(x-1)}
\\=\frac{2x-8}{(x+2)(x-1)}
\\=\frac{2x-8}{x^2+x-2}$
