Explanation
Let the speed of the train be x km/h and the speed of the car be y km/h.
Case 1: He travels 120 km by train and the rest (480 km) by car, taking 8 hours in total.
Time taken by train = Distance / Speed = 120 km / x km/h = 120/x hours
Time taken by car = Distance / Speed = 480 km / y km/h = 480/y hours
Total time = 8 hours = (120/x) + (480/y)
Case 2: He travels 200 km by train and the rest (400 km) by car, taking 8 hours 20 minutes (or 8.33 hours) in total.
Time taken by train = Distance / Speed = 200 km / x km/h = 200/x hours
Time taken by car = Distance / Speed = 400 km / y km/h = 400/y hours
Total time = 8.33 hours = (200/x) + (400/y)
Now, we have two equations and two variables. Solving them simultaneously, we get:
x = 60 km/h (speed of the train)
y = 80 km/h (speed of the car)