[Math] Knights & Knaves question

logic

I'm quite confused on how to proceed with this question.

Knights always tell the truth, and knaves lie.

You meet two people, A and B. A says, “I'm a knight
and he's a knave.” B says, “I agree.” What are they?

I'm not sure what to do with B's statement. Since B is a knave, he disagrees with the statement? Is that it?

Best Answer

They are two knaves, I mean all other options are clearly false.


Since B agrees with the statement, both are claiming that A is truthful and B is contrary.

However if that claim were true, then B would not agree.   So the claim must be false, which means both A and B must be lying.

That is, both are knaves.