Question 129891
X+Y=4 OR Y=-X+4 (RED LINE)
X=Y=-4 OR Y=-X-4 (GREEN LINE)
{{{ graph( 300, 200, -6, 5, -10, 10, -x +4, -x -4) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions -x +4 and -x -4). 
ANSWER - NO INTERSECTION=NO SOLUTION.