A moving sidewalk has a velocity of 1.3 m/s north. If a man walks south on
the sidewalk at a speed of 0.9 m/s, how long does it take him to travel 20 m
relative to a stationary observer?
O A. 21.9 s
O B. 15.4 s
O C. 33.3 s
O D. 50.0 s


Please please help!!!