[tex]\left \{ {{-x+y=12} \atop {2x-y=10}} \right.[/tex]
[tex]\left \{ {{y=12+x} \atop {2x-(12+x)=10}} \right.[/tex]
[tex]\left \{ {{y=12+x} \atop {2x-12-x=10}} \right.[/tex]
[tex]\left \{ {{y=12+x} \atop {x=22}} \right.[/tex]
[tex]\left \{ {{x=22} \atop {y=34}} \right.[/tex]
