Jen recently rode her bicycle to visit her friend who lives 12 miles away. On her way there, her average speed was 10 miles per hour faster than on her way home. If Jen spent a total of 1 hour bicycling, find the two rates.

Answer 1

since time = speed * distance, then if her outbound speed was x, then

12/x + 12/(x-10) = 1
x = 30 or 4
Check: 12/30 + 12/20 = (24+36)/60 = 1

The other solution to the equation is x=4. Why is that not useful?