Answer :
[tex]\left\{\begin{array}{ccc}3x-6y=20&|multiply\ both\ sides\ by\ 2\\2x-4y=3&|multiply\ both\ sides\ by\ (-3)\end{array}\right\\\\\underline{+\left\{\begin{array}{ccc}6x-12y=40\\-6x+12y=-9\end{array}\right}\\.\ \ \ \ \ \ \ \ \ \ \ \ \ \ 0=31\ \ \ FALSE\\\\Answer:\ No\ solution\ (x,y\in\O)[/tex]