1. The problem is to calculate the cost of carpet needed to cover the floor of a square room with side length 5 metres. 2. First, calculate the area of the square floor using the formula for the area of a square: $$\text{Area} = \text{side}^2$$ 3. Substitute the side length: $$\text{Area} = 5^2 = 25 \text{ square metres}$$ 4. To find the cost, we need the price per square metre of the carpet. Since the price is not given, let's denote the price per square metre as $p$. 5. The total cost $C$ is then: $$C = \text{Area} \times p = 25 \times p$$ 6. Therefore, the cost of the carpet needed to cover the floor is $$25p$$, where $p$ is the price per square metre of the carpet.