Puzzles/Arithmetical puzzles/Three Daughters

Puzzles | Arithmetical puzzles | Three Daughters A salesman is at the door of a family house and tries to convince the mother to buy some of his products. She says: "Well, I don't really need the products, but if you can guess how old my three daughters are I will do you a favor and buy one of them." The salesman asks the woman for a little help and she tells him: "The product of their ages is 36." As the salesman is not able to figure out the ages, she gives him another clue: "The sum of their ages is same as the number of my house." The salesman calculates for a little while but then says: "I'm sorry, Miss, but I still can't figure out their ages." The mother agrees to give him a final hint: "My eldest daughter plays piano." After that hint the salesman was able to tell the mother her daughters ages and sell one of his items. How did he figure that out? solution