# The perimeter of a square is not more than 80cm. What is the largest possible area of the square?

The largest area is $400 c {m}^{2}$
Hence it is a square with length side x then $4 x \le 80 \implies x \le 20$
The area is ${x}^{2} = x \cdot x \le 20 \cdot 20 = 400$
Hence the largest area is $400 c {m}^{2}$