Slope From Two Points

You can find the rise and the run by subtracting coordinates. This gives the slope formula. For a line through two points, the slope is the difference of the y values divided by the difference of the x values. Subtract in the same order on the top and on the bottom:

m = (y2 - y1)/(x2 - x1)

For the line through (2, 7) and (5, 1), take (5, 1) as the second point: m = (1 - 7)/(5 - 2) = -6/3 = -2. You can also take (2, 7) as the second point, and the answer is the same: (7 - 1)/(2 - 5) = 6/(-3) = -2. Either order works, as long as you use the same order on the top and on the bottom.

Do not mix the two orders. If you write y2 - y1 on top and x1 - x2 on the bottom, the slope comes out with the wrong sign. Choose one order, and use it for both subtractions.