David and john started driving towards each other at 11 am and met each other at 2 30 pm on the same day david and john started from different cities which are 420 miles apart if david average speed is 10 miles per hour lower than johns what is the speed at which john was driving in miles hours.

Aman and Kapil start from Delhi and Gwalior respectively towards each other at the same time. They meet at Mathura and then take 196 minutes and 225 minutes respectively to reach Gwalior and Delhi. If speed of Aman is 30 km/hr, what is the speed (in km/hr) or Kapil ?

A and B started travelling towards each other at the same time, from places X to Y and Y to X, respectively. After crossing each other, A and B took 2.45 hours and 4.05 hours to reach Y and X, respectively. If the speed of B was 8.4 km/h, then what was the speed (in km/h) of A?

Distance between A and B is 72km. Two men started walking from A and B at the same time towards each other. The person who started from A travelled uniformly with average speed 4 km/h.While the other man travelled with varying speed as follows In first hour,his speed was 2 km/h,in the second hour,it was 2.5km/h,in the third hour,it was 3km/h, and soon. When will they meet each other?