Question

A red light flashes every 6 seconds.

A yellow light flashes every 4 seconds.
They both flash at the same time.
After how many seconds will they next both flash at the same time?

Answer 1

Red light flashes once every 6 seconds, blue light flashes once every 10 seconds, so the next time the blue light flashes(20 seconds), the red light would have completed 18 seconds and the next time blue light flashes (30 seconds), the red light would also be flashed at the same time.

Explanation: