Sandeep covers a certain distance in 6 hours at an average speed of 30 km/hr. Sachin covers that distance in 4 hours. If Sandeep increases his average speed by 10 km/hr and Sachin increases his speed by 5 km/hr, then what will be the difference in time (in minutes) taken by them to reach their destination now?

Distance = Speed × Time = 30 × 6 = 180 km. Sandeep's new speed = 30 + 10 = 40 km/hr. New time = 180/40 = 4.5 hours = 4 hours 30 minutes = 270 minutes. Sachin's original speed = 180/4 = 45 km/hr. New speed = 45 + 5 = 50 km/hr. New time = 180/50 = 3.6 hours = 3 hours 36 minutes = 216 minutes. Difference = 270 - 216 = 54 minutes.