A and B go around a circular track of length 100 m on a cycle at speeds of 18 kmph and 36 kmph. After how much time will they meet for the first time at the starting point?	Choose the correct option:
A) 120 sec	B) 198 sec	C) 178 sec	D) 665 sec	E) 20 sec
Time taken to meet for the first time at the starting point   = LCM { length of the track / speed of A , length of the track / speed of B}   = LCM { 100/ (18 * 5/18) , 100/ (36 * 5 /18) }   = LCM (20, 10) = 20 sec.   Answer:20 sec
<result>E</result>
A and B go around a circular track of length 100 m on a cycle at speeds of 18 kmph and 36 kmph. After how much time will they meet for the first time at the starting point?