24)
B can not be the knight because for his statement to be true, A would also have to be a knight. C cannot be the knight, because then his statement would be false.
Therefore, A is the knight and by his statement, C is the Knave. This leaves B as the spy.
25)
Neither the knight nor the knave would say that he is the knave, so B must be the spy. Therefore C is lying
and must be the knave, and A is therefore the knight (and told the truth).
26)
No possible solution
27)
We know that B is not the knight, because if he were, then his assertion that A is telling the truth would
mean that there were two knights. Clearly C is not the knight, because he claims he is the spy. Therefore
A is the knight. That means that B was telling the truth, so he must be the spy. And C is the knave, who
falsely asserts that he is the spy.
28)
*If B=Knight then what options do A have =Knight or Spy but A can't be Knight because B is already Knight.
Hence A should be Spy which means C=Knave. But considering C=Knave means B=Knave which makes this assumption wrong.
*If B=knave then what option do A have =Knave which is not possible hence assuming B=Knave is also not possible.
Therefore B=Spy.
Now if we take C=knave then B would be Knave which is not possible.Hence C=knight and A=knave.
29)
We can tell nothing here; each of the six permutations is possible.
30)
A can't be the Knave, because then A is lying and thus A should be the Spy.
B can't be the Knave, because then B is lying and thus B should be the Spy.
Thus C is the only person that can be Knave.
C is lying and thus A can't be the spy. Therefore A=Knight and B=Spy.
