Answer:
Step-by-step explanation:
The term ‘elevation’ normally means the measurement above a defined point. Universally we use the 'mean sea level’ as the point of reference for measuring heights. So the airplane is considered to be at the height of 14,690 ft above the mean sea level and the submarine is at 521 ft below the mean sea level.
In case you're wondering what the height of the submarine would be in mean sea level in terms of elevation, it would just be the negative of the given depth. So, the elevation of the submarine can also be expessed as -521 ft mean sea level.
I hope i could clear your query.
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