Respuesta :

Speed = Distance / Time = 15 miles/ 6 hours = 2.5 mph

I hope it helps
Peter's average speed is 2.5 mph.

Explanation:

The formula for speed is :

Speed = Distance/Time

Since he walks 15 miles (distance) and 6 hours (time), it is speed = 15 / 6

15/6 = 2.5, therefore the average speed is 2.5 mph.