Question

Sheldon can either take a train or an airplane to San Francisco. If the train takes 9 hours and 24 minutes and the plane takes 2 hours and 39 minutes, how much time would he save taking an airplane?

Answer 1

Answer: 6 hours and 45 minutes

Work Shown

(9 hrs + 24 min) - (2 hrs + 39 min)

(8 hrs + 1 hr + 24 min) - (2 hrs + 39 min)

(8 hrs + 60 min + 24 min) - (2 hrs + 39 min)

(8 hrs + 84 min) - (2 hrs + 39 min)

8 hrs + 84 min - 2 hrs - 39 min

(8 hrs - 2 hrs) + (84 min - 39 min)

6 hrs + 45min

6 hours and 45 minutes

Notes:

• I changed "9 hrs + 24 min" into "8 hrs + 84 min" so I could borrow an hour aka 60 minutes. If this borrowing didn't happen, then we'd have 24 min - 39 min which leads to a negative number of minutes.
• 6 hrs + 45 min = 6.75 hours
• 6.75 hrs = 6.75*60 = 405 min