The expression written by Daryl is Correct.
Explanation:
Here, the given pentagon is regular Pentagon.
So, the length of all 5 sides of the pentagon is EQUAL.
Let us assume the length of each side of the pentagon = S
Now, the perimeter of the Pentagon = Sum of all its sides
or, S+ S+ S +S + S = 35 d - 25
or, 5 S = 35 d - 25
or, S =

or, S = (7 d - 5)
Hence, the each length of the pentagon is given as
(7d - 5) =

So, the expression written by Daryl is Correct.