Distance, rate, and time

Question

Melanie left Greensboro traveling sixty-nine mph. Sally, to catch up, left some time later driving at seventy-eight mph. Sally caught up after three hours. How long was Melanie driving before Sally caught up?

Answer 1

Sally drove for 3 hrs at 78 mph before catching up to Melanie. That's 234 miles.

How long for Melanie to drive 234 miles at 69 mph? 234/69 = 3.39 hrs

Answer 2

78(3) = 69(3+x)

234= 207 +69x

x= (234-107)/69=27/69= 9/23

3 hours = Sally's driving time

3 9/23 hours = about 3.3913 hours= Melanie's driving time

= about 3 hours, 23 minutes 29 seconds