The core relationship is Distance = Speed × Time — every variation of these questions is just this formula rearranged or applied to a relative-motion scenario like two objects moving toward or away from each other.
Once the base formula is second nature, most variations become a matter of correctly identifying what's being asked and rearranging accordingly: Speed = Distance ÷ Time, or Time = Distance ÷ Speed.
Question: A car travels 180 km in 3 hours. What is its speed?
Solution: Speed = Distance ÷ Time = 180 ÷ 3 = 60 km/h.
Question: Two trains, 300 km apart, move toward each other at 60 km/h and 40 km/h. When do they meet?
Solution: When moving toward each other, speeds add together: combined speed = 60 + 40 = 100 km/h. Time to meet = Distance ÷ combined speed = 300 ÷ 100 = 3 hours.
When two objects move in the same direction, their relative speed is the difference between their speeds instead of the sum — this is how "one train catching up to another" questions are solved.
Last reviewed: September 2026