[tex]\it \begin{cases} \it 3(x-1)+y=-5 \Rightarrow 3x-3+y=-5|_{+3} \Rightarrow 3x+y=-2\ \ \ \ \ \ (1)\\ \\ \it 2x+2(y+1)=6 \Rightarrow 2x+2y+2=6|_{-2} \Rightarrow 2x+2y=4|_{:2} \Rightarrow x+y=2\ \ \ \ (2)\end{cases}\\ \\ \\ (2) \Rightarrow y=2-x\ \ \ \ \ \ (*)\ (rela\c{\it t}ie\ \ de\ \ substitu\c{\it t}ie)[/tex]
[tex]\it (1)\ \stackrel{(*)}{\Longrightarrow}\ 3x+2-x=-2 \Rightarrow 3x-x=-2-2 \Rightarrow 2x=-4|_{:2} \Rightarrow x=-2\\ \\ x=-2\ \stackrel{(*)}{\Longrightarrow}\ y=2-(-2) \Rightarrow y=2+2 \Rightarrow y=4\\ \\ S=\{(-2,\ 4)\}[/tex]
