$\dfrac{x}{3}=\dfrac{y}{4}$
$→x=\dfrac{3y}{4}$
Thay $x=\dfrac{3y}{4}$ vào $xy$
$→\dfrac{3y}{4}.y=48$
$→3y^2=192$
$→y^2=64$
\(→\left[ \begin{array}{l}y=8\\y=-8\end{array} \right.\)
\(→\left[ \begin{array}{l}x=\dfrac{3.8}{4}=6\\x=\dfrac{3.(-8)}{4}=-6\end{array} \right.\)
Vậy $(x,y)=(6;8);(-6;-8)$