The slope, commonly abbreviated as
, is the change in the quantity on the y-axis, Δy, divided by the change in the quantity on the x-axis, Δx.
From the points (x, y), the first value is a value on the x-axis, and the second value after the comma is a value on the y-axis. So for the point (8, -3), 8 is x and -3 is y. But we have two points, so:
(8, -3), 8 is x1, -3 is y1
(4, -7), 4 is x2, -7 is y2
Plugging in our values, we get
So the slope,
, is equal to 1.