i don't understand why the daughters ages would be 3,3,8.
The key point is that the father told the other guy (but not us) the total age ("the same as the number on that building") and the other guy still couldn't figure out the ages. If he said that the total was 19, the guy would know that the ages were 12, 6, and 1. He must have given a total that corresponds to two or more possible sets of ages.
Thanks for clearing that up for me.
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