Answer:
- positive
- negative
- 16.8-28.1
- -11.3
Explanation:
Usually, we use positive numbers to represent "up", and negative numbers to represent "down." Then the description of the math might be ...
- The change in height between the launch point on the cliff and the distance above the cliff that the rocket reaches is best represented by a  positive  number.
- The change in height from the top height of the rocket to the ocean below the cliff is best represented by a  negative  number.
- The expression  16.8-28.1  best represents the change in height from the cliff to the ocean below.
- The change in height from the cliff to the ocean below is  -11.3  feet.