1. **State the problem:** Ling is driving at a constant speed of 55 miles per hour. We need to find how long it will take him to drive 275 miles. 2. **Formula used:** The relationship between distance, speed, and time is given by the formula: $$\text{Time} = \frac{\text{Distance}}{\text{Speed}}$$ 3. **Apply the formula:** Substitute the given values: $$\text{Time} = \frac{275}{55}$$ 4. **Simplify the fraction:** $$\text{Time} = \frac{\cancel{275}}{\cancel{55}} \times \frac{5}{5} = 5$$ 5. **Interpretation:** It will take Ling 5 hours to drive 275 miles at 55 miles per hour. **Final answer:** 5 hours