Three fences on a ranch measure 15/16 miles 7/8 miles and 7/16 miles which is the best estimate of the total length of all three fences

Of course you can answer this question in a second using the calculator, however, I'll tell you how to simply it do it manually:

First step is to make the denominator of the three terms equal:
We have two terms already having the same denominator: 15/16 and 7/16
The denominator of the third term can be changed into 16 by multiplying both the numerator and the denominator by 2 (to keep the value of the term unchanged) as follows:
7/8 x 2/2 = 14/16 miles

Now to get the total length of the three fences, we will simply add the three terms.
Since the denominators of the three terms are equal, therefore, we will add the numerators of the three terms and keep the denominator as it is in  the result.
This is illustrated as follows:
Total length of fence= 15/16 + 14/16 + 7/16 = (15+14+7)/16
                                = 36/16 miles