One inlet pipe can

Question

One inlet pipe can fill an empty pool in 8 hours, and a drain can empty the pool in 12 hours. How long will it take the pipe to fill the pool if the drain is left open?

Answer 1

fill the pool in 8 hours

drain it in 12 hours

find the prime factors

8=2^3, 12 = 3(2^2)

3(2^3) = 24

in 24 hours the pool gets filled 3 times and drained 2 times, leaving it filled in 24 hours