To find the slope between two points, we have the formula below:
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
where m = slope and x and y are the coordinates of the two points.
In the question, we have (x₁, y₁) = (-9, 9). Our (x₂. y₂) is (-3, 9).
Let's plug this in to the formula above.
[tex]m=\frac{9-9}{-3-(-9)}=\frac{0}{-3+9}=\frac{0}{6}=0[/tex]
Therefore, the slope of the line passing two points (-9, 9) and (-3, 9) is zero. This line is a horizontal line since both have the same y-coordinates.
