William travelled 9 floors up, 4 floors down, 3 floors up and 7 floors down in an elevator.
(a) What directed numbers could be used to show this journey?
(b) What single journey could he have taken to get to the final floor?
(c) Write a directed number to show this single journey.
(d) Jacinta was in an adjacent elevator travelling in the opposite direction, for each of the same movements as William. Describe the journey of her elevator.
(e) On which floor did Jacinta finish her journey?