[tex]-2x+3y=15\ldots\ldots1)[/tex][tex]-x-3y=12\ldots\ldots\ldots\ldots\text{2)}[/tex]
1)-2x2)
[tex]-2x+3y-(-2x-6y)=15-2\times12\Rightarrow-2x+3y+2x+6y=15-24\Rightarrow9y=-9\Rightarrow y=-1[/tex]
y=-1 implies
[tex]-2x+3\times(-1)=15\Rightarrow-2x-3=15\Rightarrow-2x=18\Rightarrow x=-9[/tex]
Hence the solution is
[tex](-9,-1)[/tex]
