[tex]+\left\{\begin{array}{ccc}x+2y=7\\3x-2y=-3\end{array}\right\\---------\\x+3x=7+(-3)\\4x=4\ \ \ \ /:4\\x=1\\\\\left\{\begin{array}{ccc}x=1\\x+2y=7\end{array}\right\\\left\{\begin{array}{ccc}x=1\\1+2y=7&/-1\end{array}\right\\\left\{\begin{array}{ccc}x=1\\2y=6&/:2\end{array}\right\\\left\{\begin{array}{ccc}x=1\\y=3\end{array}\right\\[/tex]
