First you find the perimeter, the length of all of the sides added together:
There are 4 sides and 2 of each of them are the measurements you stated above:
7.75*2 = 15.5
3.65*2 = 7.3
Then you add them together:
15.5+7.3 = 22.8
This means he will need 22.8ft of fence.
Hope this helps! :)
