Question 139006
4x+y=1 or y=-4x+1 (red line)
y-x=-9 or y=x-9 (green line)
{{{ graph( 300, 200, -6, 5, -10, 10, -4x +1, x -9) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions -4x +1 and x -9). 
ANSWER (2,-7).