$\begin{cases}2x+3y=5\\x-y=4\end{cases}$
$⇔\begin{cases}2x+3y=5\\2x-2y=8\end{cases}$
$⇔\begin{cases}5y=-3\\2x-2y=8\end{cases}$
$⇔\begin{cases}y=\dfrac{-3}{5}\\2x-2y=8\end{cases}$
$⇔\begin{cases}y=\dfrac{-3}{5}\\2x-2\dfrac{-3}{5}=8\end{cases}$
$⇔\begin{cases}y=\dfrac{-3}{5}\\2x+\dfrac{6}{5}=8\end{cases}$
$⇔\begin{cases}y=\dfrac{-3}{5}\\2x=\dfrac{34}{5}\end{cases}$
$⇔\begin{cases}y=\dfrac{-3}{5}\\x=\dfrac{17}{5}\end{cases}$
