Question 80781
X+Y=3, Y=-X+3
X+Y=-1, Y=-X-1
{{{ graph( 300, 200, -6, 5, -10, 10, y = -x +4, y = -x -1) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions y = -x +4 and y = -x -1). 
no common solution to these 2 euations.