Three cars driven by Mike, Scott and Jenny start driving around a circular race course of length 540m from the same point simultaneously in the same direction at speeds of 9 m/s, 15 m/s and 27 m/s respectively. When will they meet for the first time after they started moving? Pick:
A) 180 seconds B) 45 seconds C) 90 seconds D) 60 seconds E) 270 seconds
If they all meet after T seconds, it means they covered the distances 9T, 15T, and 27T respectively.   Since they all arrive to the same spot, it means that the differences taken pairwise between the distances must be positive integer multiples of the length of the track, which is 540m. So, 6T, 12T, and 18T must all be multiples of 540. 6T multiple of 540 means T multiple of 90. The smallest T with this property is 90 and is on the list of answers.   Answer 90 seconds.
<result>C</result>
Three cars driven by Mike, Scott and Jenny start driving around a circular race course of length 540m from the same point simultaneously in the same direction at speeds of 9 m/s, 15 m/s and 27 m/s respectively. When will they meet for the first time after they started moving?