Speed questions
posted by Mary on .
N city is 635 k.m. away from F city. Mr.L set off from N city to F city at 8:20 am at a speed of 70km/h. Mr.G left from f city to N city 30 min later at speed of 80km/h. At what time did they pass each other? (Both trveling on same road.)

They started out BOTH traveling towards each other at 8:50 AM, at which time Mr. L had already traveled 70/2 = 35 km, so they were 600 km apart then. The distance between them decreased at a rate of 80 + 70 = 150 km/h. Therefore they met 4 hours later, at 12:50 PM