Answer:
The whale is at a depth 120 feet below the sea level.
Step-by-step explanation:
A grey whale is cruising at a depth of 233 feet below sea level. The depth below the sea level has the negative position, thus the initial position of the whale is -233.
It rises 73 feet, the position of the whale becomes 73 feet higher. This means we should add 73.
Then it comes up another 40 feet, so we need to add 40.
Mathematically,
The whale is at a depth 120 feet below the sea level.