c/
$ \Leftrightarrow
\left\{\begin{matrix}
6x+6y=5xy\\
4y-3x=xy
\end{matrix}\right.\\\Leftrightarrow \left\{\begin{matrix}
6x+6y=5xy\\
20y-15x=5xy
\end{matrix}\right.\\\Leftrightarrow \left\{\begin{matrix}
-14y+21x=0\\
6x+6y=5xy
\end{matrix}\right.\\\Leftrightarrow \left\{\begin{matrix}
x=\dfrac{2}{3}y\\
10y=\dfrac{10}{3}y^2
\end{matrix}\right.\\\Leftrightarrow \left\{\begin{matrix}
x=2\\
y=3
\end{matrix}\right. $