Solve any two sub questions from the following : Three lighthouses flash their light after every 5 sec, 10 sec and 15 sec. They flash together at 7 : 00 p.m. When will they next flash together ?

Solve any two sub questions from the following : Three lighthouses fl

1.	Solve any two sub questions from the following : Three lighthouses flash their light after every 5 sec, 10 sec and 15 sec. They flash together at 7 : 00 p.m. When will they next flash together ?
Answer» SOLUTION :30 SEC after 7 : 00 p.m