You can put this solution on YOUR website! Y=mX+b m=slope & b=the Y intercept
3x-y+9=0 subtract 3x & 9 from both sides.
-y=-3x-9 divide both sides by -1.
y=3x+9 [3 is the slope & 9 is the Y intercept.] (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, 3x +9).