1. **State the problem:** A car moves around a circular racing track and takes 120 seconds to complete one lap of 5 kilometers. We need to find the speed of the car in kilometers per hour (km/h). 2. **Formula used:** Speed is calculated as distance divided by time. $$\text{Speed} = \frac{\text{Distance}}{\text{Time}}$$ 3. **Convert time to hours:** Since the time is given in seconds, convert it to hours because speed is asked in km/h. $$120 \text{ seconds} = \frac{120}{3600} \text{ hours} = \frac{1}{30} \text{ hours}$$ 4. **Calculate speed:** $$\text{Speed} = \frac{5 \text{ km}}{\frac{1}{30} \text{ hours}} = 5 \times 30 = 150 \text{ km/h}$$ 5. **Interpretation:** The car's speed is 150 kilometers per hour. This means the car travels 150 kilometers in one hour at this pace.