[tex] \left \{ {{x -y=129} \atop {x=10y+3}} \right. [/tex][tex] \left \{ {{10y+3-y=129} \atop {x=10y+3}} \right. [/tex][tex] \left \{ {{9y=126} \atop {x=10y+3}} \right. [/tex][tex] \left \{ {{y=44} \atop {x=10*44=3}} \right. [/tex][tex] \left \{ {{y=44} \atop {x=447}} \right. [/tex]
