Both passenger cars and freight cars leave from a and B cities. It takes 10 hours for passenger cars to complete the whole journey, 12 hours for freight cars to complete the whole journey, and 5 hours for two cars to return The distance between the two cities is 50 kilometers. How many kilometers is the difference between the two cities

Both passenger cars and freight cars leave from a and B cities. It takes 10 hours for passenger cars to complete the whole journey, 12 hours for freight cars to complete the whole journey, and 5 hours for two cars to return The distance between the two cities is 50 kilometers. How many kilometers is the difference between the two cities

The distance is x km
Then the passenger car can travel X / 10 kilometers per hour, and the freight car can travel X / 12 kilometers per hour
(x / 10) * 5 + (x / 12) * 5 + 50 = x solution
X = 600
50÷（5×1/10-5×1/12）
=50×5÷（1/10-1/12）
=10÷（6/60-5/60）
=10÷1/60
=600 km
A: the two cities are 600 kilometers apart