# Solution to the problem Given data: - Speed of the first car, \( v_1 = 50 \text{ km/h} \) - Speed of the second car, \( v_2 = 60 \{ km/h \) Both start at the same time from the same location and travel in the same direction. --- ## Step 1: Understand the problem - The relative speed between the two cars determines how quickly the distance between them increases. - Since they are moving in the same direction, the relative speed is: \[ v_{rel} = v_2 - v_1 = 60 - 50 = 10 \text{ km/h} \] --- ## Step 2: Calculate the time for the distance to be 20 km - Distance between the cars after time \( t \): \[ \text{Distance} = v_{rel} \times t \] - Set the distance to 20 km: \[ 20 = 10 \times t \] - Solve for \( t \): \[ t = \frac{20}{10} = 2 \text{ hours} \] --- ## **Answer:** \[ \boxed{2 \text{ hours}} \] **Correct choice: 2**