1. **State the problem:** We need to find what percentage 15 students represent out of 25 students. 2. **Formula:** The percentage is calculated by the formula: $$\text{Percentage} = \left(\frac{\text{Part}}{\text{Whole}}\right) \times 100$$ 3. **Apply the values:** Here, the part is 15 (students who prefer burgers) and the whole is 25 (total students). 4. **Calculate the fraction:** $$\frac{15}{25}$$ 5. **Simplify the fraction:** $$\frac{\cancel{15}}{\cancel{25}} = \frac{3}{5}$$ 6. **Convert to percentage:** $$\frac{3}{5} \times 100 = 60$$ 7. **Answer:** 15 out of 25 students represent **60%** of the class.