one gear of pulley rotates at a speed of 3 rev/sec another gear roates at 5 rev/sec. if both start together after how many seconds will they be together again Choose the correct choice
A) 3 sec  B) 5sec  C) 15 sec  D) 20 sec  E) 25 sec
3 rotates 3,6,9,12,15   5 rotates 5,10,15   ans is 15   ANSWER:15 sec
<result>C</result>
one gear of pulley rotates at a speed of 3 rev/sec another gear roates at 5 rev/sec. if both start together after how many seconds will they be together again