Having a bit of trouble grasping how to define vertical asymptotes and holes...

$\displaystyle f(x)=x^2-25/x^2+5x$

$\displaystyle f(x)=(x-5)(x+5)/x(x+5)$

$\displaystyle f(x)=x-5/x$

I get that since the leading coefficients are both 1 and the degrees are the same, the horizontal asymptote is $\displaystyle y=1$. Can someone please help me out and give me a breakdown of defining the vertical asymptote and any holes there might be? Any help is greatly appreciated!