The Clarke family went sailing on a lake. Their boat averaged 6 kilometers per hour. The Rourke family took their outboard runabout for a trip on the lake for the same amount of time. Their boat averaged 14 kilometers per hour. The Rourke family traveled 20 kilometers farther than the Clarke family. How many hour did each family spend on their boat trip?

Solution:

The time is t

14t-6t=20

t=2.5

So they travel 2.5 hours