Answer:
blue line: 20
black line: -20
Explanation:
use rise (y) over run (x)! as the blue line goes from points (8,80) to (9,100) the difference in the x or run is 1 while the difference in the y or rise is 20 which makes it 20/1 = 20. for the black line, because it's going down it indicates it will be a negative slope, use the same trick as last time, our first point is (5,20) and our next point is (6,0) the difference in x is 1 and the difference in y is -20, so -20/1 = -20! hope this helped :-)