To solve this problem first find the perimeter of the rectangle by using the formula P= 2(L+W).
Plug in your number and you get the number 28.
Now, because Noah is putting in a post at every yard and our answer is already in yards we are done.
Noah will need 28 post to build the dog run.
P=2(8+6)
P=2(14)
P=28
Hope this helps :-)