Answer:
The unit rate in miles per hour = <em>1.4 miles/hr</em>
Step-by-step explanation:
Given that:
Distance walked by Boardman family = Two over five of a mile = 
Time taken by Boardman family = Two over seven of an hour = 
To find:
The unit rate in the miles per hour = ?
Solution:
Formula for the rate or the speed can be given as:

Putting the values:

So, the unit rate in miles per hour = <em>1.4 miles/hr</em>