A boat is rowed down a river for 72 km in 9 hours and up a river for 42 km in some time. In how many hours will the boat be rowed up the river for 42 km, if the boat is running at an average speed of 7 km/h?

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.