1. The problem is to calculate the percentage of a part relative to a whole. 2. The formula to calculate percentage is: $$\text{Percentage} = \left(\frac{\text{Part}}{\text{Whole}}\right) \times 100$$ 3. To use this formula, divide the part by the whole to get a decimal. 4. Multiply the decimal by 100 to convert it to a percentage. 5. For example, if you want to find what percentage 25 is of 200: $$\text{Percentage} = \left(\frac{25}{200}\right) \times 100 = 0.125 \times 100 = 12.5\%$$ 6. So, 25 is 12.5% of 200. This method works for any values of part and whole as long as the whole is not zero.