Answer: 30 seconds
Step-by-step explanation:
From the question, we are informed that one string flashes every 10 seconds while the other one string flashes every 15 seconds.
The number of minutes that it'll take before they both flash again at the same time will be gotten by calculating the LCM of 10 and 15. This will be:
10 = 10, 20, 30, 40, 50 ...
15 = 15, 30, 45, 60, 75 ....
We can see that the lowest common multiple of 10 and 15 is 30. Therefore, the answer is 30.
They'll both flash again at same time in 30 seconds.
