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This a thing, I've seen rewards in the range of 1-20 BTC posted in other forums. Once you have control of the wallet, that user could deduct whatever they want. It's a risk for both parties.

that is assuming there is something to break! if i am right and this is indeed a wallet that is being sold, then it means it is a scam and it contains no coins whatsoever. it certainly is not going to be the first time something like this happens.
You mean to say that if someone solves this OP can use it to get access to the wallet that is sold. That means by solving one would help hacking?