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?
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.
#### 12