Answer: 0
To get that answer, apply the slope formula
m = (y2 - y1)/(x2 - x1)
m = (-8 - (-8))/(9 - (-2))
m = (-8 + 8)/(9 + 2)
m = 0/11
m = 0
Any line with slope 0 is completely horizontal.
As a quick rule of thumb: if the y coordinates of the two points are the same, then the slope is 0 on this horizontal line.