Answer
$\dfrac{x}{x+9}$
Work Step by Step
The given expression, $
\dfrac{x^2-4x}{x^2+5x-36}
,$ simplifies to
\begin{array}{l}\require{cancel}
\dfrac{x(x-4)}{(x+9)(x-4)}
\\\\=
\dfrac{x(\cancel{x-4})}{(x+9)(\cancel{x-4})}
\\\\=
\dfrac{x}{x+9}
.\end{array}
