Thelma and georgia are shopping in the city. thelma leaves for home in her car at 4:00 traveling at 54 miles per hour, but georgia doesn't leave until 4:10. if she drives at 64 miles per hour, how long after she leaves does she catch up with thelma?

So from 4.00-4.10 10minutes has passed and thelma would have travelled 10/60*54 = 9 miles. In 1 hour, georgia would have travelled 10 miles more than thelma, hence in 9/10 hours she would catch up with thelma.

9/10 * 60 = 54 minutes. hence the ans is 54 minutes or 9/10 hours