Final answer:
To calculate the time saved by taking an airplane to San Francisco, subtract the time taken by the airplane from the time taken by the train. Sheldon would save 7 hours and 39 minutes by taking an airplane.
Step-by-step explanation:
To calculate the time saved by taking an airplane, we need to subtract the time taken by the plane from the time taken by the train.
Train time = 11 hours and 23 minutes
Airplane time = 2 hours and 44 minutes
To subtract the minutes, we need to borrow 1 hour from the hours and add 60 minutes to the minutes.
Train time = 11 hours and 23 minutes = 10 hours and (23 + 60) minutes = 10 hours and 83 minutes
Airplane time = 2 hours and 44 minutes
Now, we can subtract the time taken by the airplane from the time taken by the train:
10 hours and 83 minutes - 2 hours and 44 minutes = 7 hours and (83 - 44) minutes = 7 hours and 39 minutes
Therefore, Sheldon would save 7 hours and 39 minutes by taking an airplane to San Francisco.