Answer:
C
Explanation:
Because the dolphin increases his elevation, the amount he increases is added to the original elevation to get the second elevation.
Therefore:
-16 3/4 + 5x = -5 1/4
This option is not in the options but if we rearrange the left side from
- 16 3/4 + 5x
to:
5x - 16 3/4
We get the last option C.
Hope this helped!