With the help clues provided in the image, can you find the 5 digit key?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

f you were running a race, and you passed the person in 2nd place, what place would you be in now?

Count the number of triangles in the below picture?

What has to be broken before you can use it?

Which English verb becomes past tense just by rearranging the letters?

If,

20 % 5 = 24

21 % 7 = 33

42 % 6 = 67

Then;

66 % 6 = ?

A wealthy man lives alone in a small cottage. Being partially handicapped he had everything delivered to his cottage. The mailman was delivering a letter one Thursday when he noticed that the front door was ajar. Through the opening he could see the man's body lying in a pool of dried blood. When a police officer arrived he surveyed the scene. On the porch were two bottles of warm milk, Monday's newspaper, a catalog, flyers, and unopened mail. The police officer suspects it was foul play. Who does he suspect and why?

what does the below rebus mean?

Forwards I am heavy, backward I am not. What am I?