If anyone could explicitly show me the steps of how this substitution works I'd be v. grateful

$\displaystyle

\frac{{dy}}

{{dx}} = \frac{{x^2 + y^2 + 9xy}}

{{9x^2 }} \Rightarrow \frac{{dy}}

{{dx}} = \frac{1}

{9}(1 + (\frac{y}

{x})^2 ) + \frac{y}

{x}

$