Calculate Square Area from Perimeter

The problem provides the perimeter of a square and asks for its area.

Given: Perimeter of the square, $P = 20 \text{ cm}$.

The perimeter of a square is calculated using the formula:

$P = 4s$

where $s$ is the length of one side of the square.

We can find the side length ($s$) by rearranging the formula:

$s = \frac{P}{4}$

Step-by-Step Calculation

1. Calculate the side length:

   Substitute the given perimeter into the formula:

   $s = \frac{20 \text{ cm}}{4}$

   $s = 5 \text{ cm}$

2. Calculate the area:

   The area of a square is calculated using the formula:

   $A = s^2$

   Substitute the calculated side length into the area formula:

   $A = (5 \text{ cm})^2$

   $A = 25 \text{ cm}^2$

Therefore, the area of the square is $25 \text{ cm}^2$. This matches Option 3.