Answer: 2.5 miles per hour (mph)
To get this answer, divide 10 over 4
10/4 = 2.5
You can think of it in terms of this ratio
10 miles: 4 hours
If we divide both parts of that ratio by 4, then we'll have
10 miles: 4 hours
(10/4) miles: (4/4) hours
2.5 miles: 1 hour
Therefore, in one hour, you can walk 2.5 miles. The unit rate is basically the speed in which you can do a task in one unit of time, in this case how far you can walk in 1 hour.