Answer
$\dfrac {dy}{dx}=\dfrac {\tan y}{1-xsec^2y}$
Work Step by Step
$x\tan y=y-1\Rightarrow \dfrac {d}{dx}\left( x\tan y\right) =\dfrac {d}{dx}\left( y-1\right) \Rightarrow \tan y+xsec^2y\times \dfrac {dy}{dx}=\dfrac {dy}{dx}$
$\Rightarrow \dfrac {dy}{dx}=\dfrac {\tan y}{1-xsec^2y}$
