Kamal started his road trip in his car and moved at a constant speed of 75 km/h. After completing x% of his total journey, his car started malfunctioning, and therefore, he had to complete the remaining journey at half of his normal speed. What is the average speed (in km/h) of Kamal's whole journey, in terms of x?

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.