To convert the speed from kilometers per hour (km/h) to miles per hour (mph), you can use the conversion ratio of 1 kilometer equals approximately 0.62 miles.
Given that the car travels at a speed of 120 km/h, you can calculate the speed in mph as follows:
\[ \text{Speed in mph} = \text{Speed in km/h} \times \text{Conversion factor} \]
\[ \text{Speed in mph} = 120 , \text{km/h} \times 0.62 , \text{miles/km} \]
\[ \text{Speed in mph} = 120 \times 0.62 = 74.4 , \text{mph} \]
Therefore, the speed of the car in miles per hour is approximately 74.4 mph.