You can put this solution on YOUR website!
2X-Y=4 -Y=-2X+4 Y=2X-4 (RED LINE)
2X-Y=6 -Y=-2X+6 Y=2X-6 (GREEN LINE)
(graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions y = 2x -4 and y = 2x -6).
these 2 lines are paralllel thus there is no unique solution to these 2 equations.