[tex]\displaystyle 1)\left \{ {{x+y=14} \atop {x-y=8}} \right\\\\\left \{ {{x+y=14} \atop {x=8+y}} \right.\\ \\8+y+y=14\\ y=3\\x=8+3\\x=11\\(x,y)=(11,3)\\\\2)\left \{ {{x-y=9} \atop {x+y=29}} \right.\\ \\\left \{ {{x-y=9} \atop {x=29-y}} \right. \\\\29-y-y=9\\y=10\\x=29-10\\x=19\\(x,y)=(19,10)[/tex]