Hey there!
Perimeter is the combination of all the sides.
side+side+side+side= P
We know that P, or perimeter, is 14 yards.
And we know that one side is 4 yards.
4 * 2= 8 (we know two sides have to be the same)
14-8= 6
Now we have 6 yards left and two sides. So, we should divide by two.
6/2=3
x=3
I hope this helps!
~kaikers