\[y = \frac{x^{2} - 16}{x - 4} - \frac{2x^{2} - x}{x} =\]
\[= \frac{(x - 4)(x + 4)}{x - 4} - \frac{x(2x - 1)}{x} =\]
\[= x + 4 - (2x - 1) = x + 4 - 2x + 1 =\]
\[= - x + 5;\ \ \ \ x \neq 4,\ x \neq 0.\]