[tex]\it \begin{cases} \it \dfrac{9(1-x)}{4}+\dfrac{y}{6}=5|_{\cdor12} \Rightarrow 27-27x+2y=60|_{-27} \Rightarrow -27x+2y=33\\ \\ \\ \it \dfrac{3x}{2}-\dfrac{y+1}{8}=-2|_{\cdot8} \Rightarrow 12x-y-1=-16 \Rightarrow y=12x+15\ \ \ \ \ (*) \end{cases}\\ \\ \\ -27x+2y=33\ \stackrel{(*)}{\Longrightarrow}\ -27x+2(12x+15)=33 \Rightarrow -27x+24x+30=33|_{-30} \Rightarrow\\ \\ \Rightarrow -3x=3|_{:(-3)} \Rightarrow x=-1[/tex]
[tex]\it x=-1\ \stackrel{(*)}{\Longrightarrow}\ y=-12+15 \Rightarrow y=3\\ \\ S=\{(-1,\ 3)\}[/tex]
[tex]\it \rule{90}{0.9}\\ \rule{70}{0.4}[/tex]
