A logician asks a woman the age of her 3 children. She says: "The product of their age is 36". The logician says he does not know the answer. The woman then says "The sum of their age is equal to the number of that house over there". The logician says he still doesn't know the answer. After that, she says: "The oldest plays the piano". The logician says: "Now I know the answer". What's the age of the children? You should be able to solve this.