Answer: 0
Step-by-step explanation:
Since the line is horizontal and the y-values don't change, the slope is 0. The slope represents the change in y-values, but since the y-values are the same for all x values, there is no change and the slope is 0.
You can check this by picking two points and finding the slope through (y2-y1)/(x2-x1)
if we use the points (3,5) and (4,5) we get that the slope is (5-5)/(4-3) = 0/1 = 0
