25. One caution sign flashes every 4 seconds, and another caution sign flashes every 10 seconds. At a certain instant, the 2 signs flash at the same time. How many seconds elapse until the 2 signs next flash at the same time?

Answer and Explanation

Your Answer is

Correct Answer is D

Explanation

Equivalent to finding the least common multiple of 4 and 10, which is 20.