The Change in the y-coordinate with respect to change occurring in the x-coordinate is known as slope a line. The net change in the x-coordinate is Δx. Likewise, the net change in the y-coordinate is Δy. Hence, the slope of a line can be written as: m = Δy/Δx. Here, m is the slope, Δx is the net change in the x-coordinate and Δy is the net change in the y-coordinate. Based on the relationship of the two variables of x and y, slope of a line is classified into four types. They are: Undefined Slope, Zero Slope, Negative Slope and Positive Slope.