45 seconds. Since there are 60 seconds in a minute and 60/4 is 15. 15*3 is 45. Hope this helped!
Answer:
168 seconds
I edited the answer.
Step-by-step explanation:
To find the the time taken for both lights to flash at the same time, we need to find the lowest common multiple of 28 and 24.
28 x 6 = 168, 24 x 7 = 168
The LCM of 28 and 24 is 168.
So it takes 168 seconds for both lights to flash at the same time.