The perimeter \( P \) of a rectangle can be calculated using the formula:
\[ P = 2 \times (\text{length} + \text{breadth}) \]
For a rectangle with a length of 10 cm and a breadth of 5 cm, the calculation would be:
\[ P = 2 \times (10 , \text{cm} + 5 , \text{cm}) \] \[ P = 2 \times 15 , \text{cm} \] \[ P = 30 , \text{cm} \]
Thus, the perimeter of the rectangle is 30 cm.