You'll need either
- a) Two points, or
- b) The slope and a point the line goes through
To be able to find the equation of a line. If you go with option a), then you can use the slope formula to get the slope. From there you effectively move to option b). If you already know the slope, then use option b) and there's no need to use option a) at all.
You can use y = mx+b which is slope intercept form or you could use point slope form y-y1 = m(x-x1) as the equation to help find the line.
The slope formula is m = (y2-y1)/(x2-x1)
