Through the first pipe, the pool is filled in 20 hours, and through the second in 30 hours.

Through the first pipe, the pool is filled in 20 hours, and through the second in 30 hours. How many hours will the pool be filled through both pipes.

To find the time of filling the pool with two pipes, an equation can be drawn up, since it is known that through the first pipe the pool is filled in 20 hours, and after the second one – in 30 hours.
Let’s designate as x – the required time, then we have:
1/20 + 1/30 = 1 / x;
3/60 + 2/60 = 5/60 = 1/12
x = 12 hours.
Answer: It will take 12 hours to fill the pool through two pipes.