[tex]\begin{cases}2x+y=18 \ \ | \ multiply\ both\ sides\ by\ (-2 ) \\ 4x+3y=18 \end{cases}\\\\\begin{cases}-4x-2y=-36 \\ 4x+3y=18 \end{cases}\\+--------\\y=-18\\\\2x-18=18\ \ | \ add\ 18\ to\ both\ sides \\ 2x=36 \ \ / | \ divide \ both \ sides\ by\ 2\\x=18\\\\Answer: \ \ \begin{cases} x=18 \\ y=-18 \end{cases} [/tex]
[tex]graph : \\\\\begin{cases}2x+y=18 \\ 4x+3y=18 \end{cases} \\\\\begin{cases} y=-2x+18 \\ 3y=-4x+18\ \ | \ divide \ each \ term \ by \ 3 \end{cases} \\\\\begin{cases} y=-2x+18 \\ y=-\frac{4}{3}x+6\end{cases}[/tex]
