If Hoses $$\text{A}$$ and $$\text{B}$$ are turned on at the same time, they will take $$9$$ hours to fill a swimming pool. It takes Hoses $$\text{A}$$ and $$\text{C}$$ $$12$$ hours to fill the same pool. Hoses $$\text{B}$$ and $$\text{C}$$ will take $$18$$ hours to do the same job. How many hours will it take to fill the pool if all the three hoses are turned on at the same time? 
Overseas Competition->Knowledge Point->Word Problem Modules->Work Word Problems->Pool Filling and Draining Word Problems