[tex]\displaystyle\bf\\+\left \{ {{-3x+6y=-9} \atop {3x+y=23}} \right. \\----------\\7y=14\\\\y=14:7=2\\\\3x=23-y=23-2=21\\\\x=21:3=7\\\\\\Otvet \ : \ (7 \ ; \ 2)[/tex]