[tex]\displaystyle 1)\left \{ {{7x+2y=26} \atop {x-3y=-16}} \right.\\ \\\left \{ {{7x+2y=26} \atop {x=-16+3y}} \right.\\ \\7(-16+3y)+2y=26\\y=6\\x=-16+3*6\\x=2\\(x,y)=(2,6)\\\\2)\left \{ {{7x+y=-13} \atop {x+7y=5}} \right. \\\\\left \{ {{y=-13-7x} \atop {x+7y=5}} \right. \\\\x+7(-13-7x)=5\\x=-2\\y=-13-7(-2)\\y=1\\(x,y)=(-2,1)[/tex]