Answer
$\frac{x^{2}-6x-4}{(x-1)(x+2)(x-4)}$
Work Step by Step
We form a common denominator, then add, factor, and simplify:
$\displaystyle \frac{x}{x^{2}+x-2}-\frac{2}{x^{2}-5x+4}=\frac{x}{(x-1)(x+2)}+\frac{-2}{(x-1)(x-4)}
=\frac{x(x-4)}{(x-1)(x+2)(x-4)}+\frac{-2(x+2)}{(x-1)(x+2)(x-4)}=\frac{x^{2}-4x-2x-4}{(x-1)(x+2)(x-4)}=\frac{x^{2}-6x-4}{(x-1)(x+2)(x-4)}$