1. The problem asks: What percentage of 110 is 55? 2. To find what percentage one number is of another, use the formula: $$\text{Percentage} = \left(\frac{\text{Part}}{\text{Whole}}\right) \times 100$$ 3. Here, the "Part" is 55 and the "Whole" is 110. 4. Substitute the values into the formula: $$\text{Percentage} = \left(\frac{55}{110}\right) \times 100$$ 5. Simplify the fraction: $$\text{Percentage} = \left(\frac{\cancel{55}}{\cancel{110}}\right) \times 100 = \frac{1}{2} \times 100$$ 6. Multiply to find the percentage: $$\text{Percentage} = 50$$ 7. Therefore, 55 is 50% of 110.