The first pump has a rate of 1/3 a day.
The second pumo has a rate of 1/9 a day.
If both pumps are working together then the total rate is:
![(1)/(3)+(1)/(9)=(9+3)/(27)=(12)/(27)](https://img.qammunity.org/2023/formulas/mathematics/college/6eqzgupdrhoip4x5pphelf1hpkegrkq61b.png)
each day.
Then it will take a total of:
![(27)/(12)=2.25](https://img.qammunity.org/2023/formulas/mathematics/high-school/xsdc9lcdf2tfesxgj9q6guf6o0q35yr95y.png)
Therefore it will take the two pumps 2.25 days to emprty the pool together.