A boat goes 24 km upstream and 28 km downstream in 6 hours. It goes 30 km upstream and 21 km downstream in 6 hours and 30 minutes. What is the speed of the boat in still water?

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.