Hamilton rides 12 miles downhill, then back uphill at 8 mph slower, taking 2 hours longer. His downhill speed is:

1. Downhill at 12 mph takes 1 hour. 2. Uphill at 4 mph takes 3 hours. 3. The gap is 2 hours, so downhill is 12 mph. _Source: OpenStax Elementary Algebra, Chapter 8, Solve Uniform Motion and Work Applications._