15 minutes is 15/60=<<15/60=0.25>>0.25 hours.

Traveling 15 minutes at 16 miles per hour, Stephen travels 16*0.25 = 4 miles.

Traveling 15 minutes at 12 miles per hour, Stephen travels 12*0.25 = 3 miles.

Traveling 15 minutes at 20 miles per hour, Stephen travels 20*0.25 = 5 miles.

All together, Stephen travels 4+3+5=<<4+3+5=12>>12 miles.

# Answer

12
Question:
Stephen rides his bicycle to church.  During the first third of his trip, he travels at a speed of 16 miles per hour. During the second third of his trip, riding uphill, he travels a speed of 12 miles per hour.  During the last third of his trip, he rides downhill at a speed of 20 miles per hour.  If each third of his trip takes 15 minutes, what is the distance Stephen rides his bicycle to church, in miles?
Answer:
Let's think step by step.

user
12
Stephen rides his bicycle to church.  During the first third of his trip, he travels at a speed of 16 miles per hour. During the second third of his trip, riding uphill, he travels a speed of 12 miles per hour.  During the last third of his trip, he rides downhill at a speed of 20 miles per hour.  If each third of his trip takes 15 minutes, what is the distance Stephen rides his bicycle to church, in miles?
train