This is late, sorry. But the formulas are in slope-intercept form. Not really original, because the fraction is the slope, and the + or - is the Y-intercept. To find the slope, find 2 places that the line intersects with the the corners of the paper. (Idk how to explain that part). The slope formula is rise over run. After you've found those 2 points on the paper, find how many points it takes to get down, and then find how many points it takes to get across. Simplify that fraction if needed. Them for the y intercept. All u have to find is what number the line intersects with on the y axis. Make the slope negative because the line is decreasing. Hope I helped! :)
