Answer:
108 miles
Explanation:
For this problem you can create a proportion:

To find how many miles it flies in 3 hours, we need to find the unit fraction. Do this by making the denominator (bottom number) 1:
here, we must divide by 13:
÷
=

Each hour, they fly 36 miles.
To find how many miles they fly in 3 hours, make a proportion:
=

Then, solve:
use cross multiplication:
36·3=108
x·1=x
108=x