[tex]\displaystyle 1)\left \{ {{6x+y=0} \atop {7x+9y=47}} \right.\\ \\\left \{ {{y=-6x} \atop {7x+9y=47}} \right. \\\\7x+9(-6x)=47\\x=-1\\y=-6(-1)\\y=6\\(x,y)=(-1,6)\\\\2)\left \{ {{x+6y=15} \atop {5x+4y=-3}} \right. \\\\\left \{ {{x=15-6y} \atop {5x+4y=-3}} \right. \\\\5(15-6y)+4y=-3\\y=3\\x=15-6*3\\x=-3\\(x,y)=(-3,3)[/tex]