That was pretty clever, how you neatly and cleanly cut off the part of the photo that shows the formula we're supposed to use.
At time=0, the position is zero, and at time=5 sec, the position is 20 m.
Slope = (change in position)/(change in time)
Slope = (20m - 0m) / (5s - 0s)
Slope = (20m) / (5s)
Slope = 4 m/s
