I’m not sure but this is what I would do
Runner A (unit rate / constant of proportionality):
54 feet divided by 4.5 seconds = 12 feet per second
Runner B (unit rate / constant of proportionality): 300 feet divided by 20 seconds (It looks like the end point of the line lands between 300 feet and 20 seconds) = 15 feet per second
Unit Rate:
Runner A = 12 feet per second
Runner B = 15 feet per second
Faster Runner:
Runner B is the faster runner as he can run a further distance than Runner A in one second.