Through the first pipe, the pool is filled in 14 hours, through the second pipe, the pool is filled

Through the first pipe, the pool is filled in 14 hours, through the second pipe, the pool is filled in 35 hours. How many hours will it take to fill the pool through 2 pipes?

We take the volume of the pool as 1.

The first pipe fills 1/14 of the pool in 1 hour.

The second pipe fills 1/35 of the pool in 1 hour.

We find which part of the pool both pipes fill in 1 hour at the same time.

(1/14) + (1/35) = (35 + 14) / (14 * 35) = 49 / (14 * 35) = 1/10;

Find how long it takes for both pipes to fill the pool at the same time.

1: (1/10) = 10;

Answer: in 10 hours.