Answer:
The rate of change of the divers elevation is approximately 24.71 feet/minute
Step-by-step explanation:
The given information are;
The depth to which the scuba diver dove =
The rate at which he dove = -21.3 feet/minute
The time which he spent at that elevation = 10.5 minutes
The elevation the diver then ascended to = 
The total time for the dive = 
Therefore, the time,
, with which the scuba diver descended to
is given as follows;

The time,
, it took the scuba diver to elevate to
is given as follows;
=
- (3.75 + 10.5) minutes ≈ 2.8738 minutes
The rate of change of the divers elevation = (Final elevation - Initial elevation)/(Time taken)
∴ The rate of change of the divers elevation = (
- (
))/(2.87 minutes) = 71/2.8738 ≈ 24.71 feet/minute to the nearest hundredth
The rate of change of the divers elevation ≈ 24.71 feet/minute.