You and a friend each drive 50.0 km. You travel at 90.0 km/hr and your friend travels at 95.0 km/hr. How long will your friend have to wait for you at the end of the trip?

Find the time taken by you and your friend separately, using the distance/time/speed formula:

Time = Distance / Speed

Then find the difference to get the time your friend has to wait. :)