Logic Puzzle: 

There are three people (Alex, Ben and Cody), one of whom is a knight, one a knave, and one a spy. The knight always tells the truth, the knave always lies, and the spy can either lie or tell the truth.

Alex says: “Cody is a knave.”
Ben says: “Alex is a knight.”
Cody says: “I am the spy.”

Who is the knight, who the knave, and who the spy?

Answer: 

• We know Ben isn’t telling the truth because if he was, there would be two knights; so Ben could be either the knave or the spy.
• Cody also can’t be the knight, because then his statement would be a lie.
• So that must mean Alex is the knight.
• Ben, therefore, must be the spy, since the spy sometimes tells the truth;
• leaving Cody as the knave.

Triangle Puzzle: 

How many triangles are there?

Answer: 

The answer is lucky number 24—25 if you want to get fussy.

Resource:
https://www.rd.com/article/triangle-puzzle/

https://www.quora.com/How-many-triangles-are-in-this-picture-1/answer/Martin-Silvertant?srid=IfHo

Did you notice this triangle?

Chess Puzzle: 

Mate in Three Moves, White to Play

Answer: 

https://chesspuzzlesonline.com/solution/ps141/