90 किमी की दूरी तय करने में, R को S से 4 घंटे अधिक लगते हैं। यदि R अपनी गति को तीन गुना कर देता है, तो उसे S से 2 घंटे कम लगेंगे। R की मूल गति (किमी/घंटा में) क्या है?

Rohan walks around a circular field at the rate of 1 round per hour while Shreyas runs around it at the rate of 5 rounds per hour. They start in the same direction from the same point at 8:30 AM. When will they first cross each other?

The traffic lights at three different road crossings change after every 24 seconds, 36 seconds, and 54 seconds respectively. If they all change simultaneously at 09:15:00 hours, at what time will they next change simultaneously?