Kara and Steven are biking around a 1,800 kilometer path. They start biking from the same place, at the same time, and in the same direction. Kara bikes at a speed of 15 km/h and Steven bikes at a speed of 30 km/h. How long will it take before Steven and Kara will be at the same place of the path next time?

Accepted Solution

Steven consistently goes 15 km/h faster than Kara does. Therefore, every hour, he gains another 15 km of distance ahead. This goes on until the first time they meet, at which case Steven will have gone an extra full lap of 1800 km, which will put them at the same location at the same time. We divide 1800 km / 15 km/h = 120 hours.