Below is an instruction that describes a task. Write a response that appropriately completes the request in Swahili. Please answer in Swahili.

### Instruction:
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?

### Response:
 Dakika 15 ni 15/60 = <<15/60=0.25>>0.25 saa.
Kusafiri dakika 15 kwa kasi ya maili 16 kwa saa, Stephen anasafiri maili 16 * 0.25 = 4.
Kusafiri dakika 15 kwa kasi ya maili 12 kwa saa, Stephen anasafiri maili 12 * 0.25 = 3.
Kusafiri dakika 15 kwa kasi ya maili 20 kwa saa, Stephen anasafiri maili 20 * 0.25 = 5.
Jumla, Stephen anasafiri maili 4 + 3 + 5 = <<4+3+5=12>>12.