[tex]\left \{ {{2x+y=-1} \atop {6x+4y=0}} \right. = >[/tex][tex]\left \{ {{y=-1-2x} \atop {6x+4y=0}} \right.[/tex][tex]= > \left \{ {{y=-1-2x} \atop {6x+4*(-1-2x)=0}} \right. = >[/tex][tex]\left \{ {{y=-1-2x} \atop {6x-4-8x=0}} \right. = > \left \{ {{y=-1-2x} \atop {-2x-4=0}} \right. = > \left \{ {{y=-1-2x} \atop {-2x=4}} \right. = > \left \{ {{y=-1-2x} \atop {x=-2}} \right. = > \left \{ {{2*-2+y=-1} \atop {x=-2}} \right. = > \left \{ {{-4+y=-1} \atop {x=-2}} \right. = > \left \{ {{y=3} \atop {x=-2}} \right.[/tex]
