Did you read the comment? He said they were considered unsolvable at the time, not that they were unsolvable. Of course they're solvable - they were solved.
That is precisely my point. They were not considered "unsolvable" (i.e. impossible to solve), they were considered "unsolved" (i.e. not solved yet) and were presented as such. Do you really need me to explain distinctions in meaning here?
http://www.snopes.com/college/homework/unsolvable.asp