My version, complete with an answer, goes like this:
A man died and bequeathed his 17 cows to his 3 sons on the following plan: the oldest son was to get (1/2) of the cows, the second was to get (1/3) of the cows, and the youngest son was to get (1/9). The will did not allow the sons to sell or slaughter the cows or depart from the specified amounts. The sons wanted to comply with the will but could see no way to fulfill these terms. What to do?
An answer: if there were 18 cows instead of 17, then the oldest son would take 9 cows, the second son 6 cows, and the third son 2 cows; this is a total of 17, the actual number of cows in the estate. So take these numbers.
When and where was this riddle first posed? Are there versions of the riddle recorded during the Renaissance? The Middle Ages?