to graph a line, all you need is two points, we already know the line goes through (3, -4), and we know its slope is -2 or -2/1, so simply "run it by 1 unit" and "rise it by -2 units", to get a second point,
[tex]\bf slope=\cfrac{\stackrel{rise}{-2}}{\stackrel{run}{1}}\qquad(\stackrel{x}{3},\stackrel{y}{-4})\qquad \qquad (\stackrel{x+1}{4}~~,~~\stackrel{y-2}{-6})[/tex]
that's the second point, now just run the line through those two.
