Pinned Questions of logic/mathematics/lateral thinking

Well, I think it is better to give the solution and someone else put another question.
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x years = age of mother
y years = age of son.

The question enunciating

x = y + 21 and (x + 6) = (y + 6) x 5

x + 6 = 5y + 30,, x = 5y + 24

Then:

y + 21 = 5y + 24,, 21- 24 = 5y - y,, -3 = 4y,, y = -(3/4) years.

But

-(3/4) years = -9 months.

And

-9 months = missing 9 months to the son be born.

And now the question has sense:

The father is ´making´ the son over the mother (hahahahaaaa).

I, III, II
K, R, M
UIWGFCTYXGAGURGWGLDKBRRERXYURSQMEHYTOUOAFPRDNYNJLGRGTNCZFXJYVFISGQMLOHRTANQUU

Enigmatic message. Can you decode it?.

1st clou: There is a clou in the own text of the post.

2nd clou: The first who broke the code not were English, he was a Polish mathematician, Marian Rejewski.

Another clue: There are some simulators on Internet, I have used one on Flash.

Today, I propose a challenge: you have to put 6 nails on the head of a 7th without falling, and of course without leaning on the ground.There is no trick, no play on words, normal nails and currents all the same, I insist: 6 nails on the head of a 7th nail.

If they needed 8 men to build a wall in 10 hours, how long would it take for 4 men to build the same wall?.

What is better than God, more evil than the Devil, the poor have it, the rich need it, and if you eat it you will die?.

Why Chinese children eat more rice than Japanese children?.

What is the instrument of the orchestra for which no wind, no percussion, no string is used?.

Sorry Kellogen, it is not a Theremin.

A classical orchestra.

MARTA and MARIA say:

We are daughters of the same father and the same mother, but we are not sisters.

What are MARTA and MARIA?.

No Kellogen, they are not grandchildren.

You have to think differently, non-linear, ... lateral thinking.

Following an anonymous call, the police enter a house to arrest an alleged murderer.

They do not know what he's like, but they know his name is John and he's inside the house.

The police find four people playing poker: one is engaged in carpentry, the other handles a truck, the other works in a mechanic's workshop and the latter works in the fire station.

Without any questions and without hesitation, they immediately arrest those who work at the fire station.

How were they sure they arrested the right person?.

A man is at the beginning of a long corridor that has three switches, at the end there is a room with the door closed.

One of these three switches turns on the light of that room, which is initially turned off.

How did you know which switch turns the light on, walking only once in the corridor?.


Clou: The man has a flashlight.

If someone wants to know the answer to any question, you can request it in a post in this thread.

Do you see something strange in this photo?.