Final answer:
The difference in elevation between the volcano and the oceanic trench is 7,762 feet.
Step-by-step explanation:
To find the difference in elevation between the volcano and the oceanic trench, we subtract the elevation of the trench from the elevation of the volcano. In this case, the volcano has an elevation of 13,876 feet and the trench has an elevation of 21,638 feet below sea level. Subtracting the trench elevation from the volcano elevation, we get a difference of 7,762 feet.