Answer:
B) 23 hours
Step-by-step explanation:
He already traveled 720 miles in 12 hours.
His average speed is (720 miles)/(12 hour) = 60 mph
The entire trip is 2100 miles. He already traveled 720 miles.
2100 miles - 720 miles = 1380 miles.
The time it takes to travel 1380 miles at 60 mph is:
(1380 miles)/(60 mph) = 23 hours
Answer: B) 23 hours