Trucks 240 km apart: 50 and 30 km/h

Two trucks start 240 km apart and drive toward each other at 50 km/h and 30 km/h. After how many hours do they meet?

Step-by-step

1. 50 + 30 = 80
   Moving toward each other, the relative speed is the sum of the speeds
2. 240 ÷ 80 = 3
   Time to meet head-on = distance ÷ relative speed

Why it works

Driving toward each other, the two trucks close the gap at the sum of their speeds, so the meeting time is the total distance divided by that sum.

Common mistakes

• Subtracting the speeds instead of adding them.
• Dividing 240 km by only one truck's speed.

Related

meeting-problem meeting-cars-360km-80-40 meeting-trains-900km-100-80