Answer :
[tex]\left\{\begin{array}{ccc}x-2y=1\\x+4y=7&/\cdot(-1)\end{array}\right\\\\+\left\{\begin{array}{ccc}x-2y=1\\-x-4y=-7\end{array}\right\\-----------\\.\ \ \ \ \ \ \ \ \ -6y=-6\ \ \ \ \ /:(-6)\\.\ \ \ \ \ \ \ \ \ \ \ \ \ \ y=1\\\\x-2\cdot1=1\\x-2=1\\x=1+2\\x=3\\\\Answer:\\\left\{\begin{array}{ccc}x=3\\y=1\end{array}\right[/tex]
