Answer
$\dfrac{-5x+40}{x^2+2x-8}$
Work Step by Step
The expressions are not similar. Make them similar by using the LCD, which is $(x-2)(x+4)$, to have:
$\\=\frac{5(x+4)}{(x-2)(x+4)} -\frac{10(x-2)}{(x+4)(x-2)}
\\=\frac{5x+20}{(x-2)(x+4)}-\frac{10x-20}{(x-2)(x+4)}
\\=\frac{5x+20-10x-(-20)}{(x-2)(x+4)}
\\=\frac{-5x+40}{(x-2)(x+4)}
\\=\frac{-5x+40}{x^2+2x-8}$
