Answer:
0
Explanation:
The slope of a line is obtained thus :
Slope = Rise / Run
Rise = (x2 - x1)
Run = (y2 - y1)
x2 = 3 ; x1 = 0
y1 = - 20 ; y2 = - 20
Slope = (-20 - (-20)) / (3 - 0)
Slope = (-20 + 20) / 3
Slope = 0 / 3
Slope = 0
Hence, the slope or rate of change = 0