A train travelling at a speed of 84 km/h passes a post in 9 seconds and a platform in 30 seconds. What is the length of the platform?

In a 1 km race, A runs at a speed of 35 m/s. If A gives B a start of 50 m and beats him by 12 seconds, then the speed of B is:

The speed of a car is 20 m/s. How much distance (in km) will the car travel in 2.5 hours?

If Reena walks from her home at a speed of 3 km/h, she reaches a birthday party 20 minutes late. If she increases her speed to 4 km/h, she reaches 30 minutes early. What is the distance between her home and the party venue?