[tex] \left \{ {{3x-2y=9\ /\cdot(-1)} \atop {5x-2y=7\ \ \ \ \ \ \ \ }} \right.\\\\ \left \{ {{-3x+2y=-9} \atop {5x-2y=7}} \right. \\--------\\-3x+5x=-9+7\\2x=-2\ /:2\\x=-1\\ \\5x-2y=7\\ 2y=5x-7\ \ \Rightarrow\ \ \ y= \frac{1}{2}\cdot[ 5\cdot(-1)-7]= \frac{1}{2}\cdot(-12)=-6\\ \\ \left \{ {{x=-1} \atop {y=-6}} \right. [/tex]
