Question 345544
You need to know the length and width first. Since it is a square then the sides are equal.
Therefore,
P=2L+2W
10n=4s
s=10n/4 or 5/2 n
The length of one side is 5/2 n. 
The area is
A=s^2
A=(5/2 n)^2
=25/4 n^2