A man takes 20 hours to go to a place and come back by walking both ways. He could have saved 4 hours by riding both ways. If the distance covered in the entire round-trip journey is 36 miles, find his average speed for the whole journey if he goes by walking and comes back by riding.

Ramesh covers 56 part of the total distance by bus and the remaining 36 km by car. What is the total distance of his journey?

A person covers a distance of L km in 12 hours. If he increases his speed by 10 m/s, he covers the same distance in 8 hours. Which of the following statements is/are correct? I. The value of L is 760 km. II. The original speed of the person is 72 km/h.