A building's elevator initially starts on the ground floor. It moves 21.6 m upwards to the sixth floor. It then goes down 7.20 m to the fourth floor. Finally, it goes up another 18.0 m to the ninth floor. The whole trip takes 134 seconds to complete. Assume up is the positive direction.
a) What distance did the elevator travel?
b) What was its total displacement?
c) What is the average speed?
d) What is the average velocity?