Time and Distance - General Questions

A car travels from A to B at 35 km/hr and returns from B to A at 140 km/hr. What is the average speed for the whole journey?

How far does a cyclist travel in 30 minutes at a speed of 40 km/hr?

A car covers 420 km in 3 hours. At what speed must it travel to cover the same distance in 2 hours?

Walking at 4/5 of his usual speed, a man is 6 minutes late. What is his usual time to cover the distance?

A car covers 360 km in 3 hours. At what speed must it travel to cover the same distance in 2 hours?