So from what I understand, you would multiply 10m by 5m for the width to get 50m squared, and multiply the 50 by 2 to get 100m for both sides of the width for the pool. Next the length. Multiply 25m by 2.5m to get 62.5m squared. Once again, mutiply it by 2 for both side lengths of the pool to get 125m. Last, add 125m and 100m to get 225m for the concrete border of the pool.
