Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

Can you decipher the following common phrase?

T M C
A U O
H S M
W T E

Which alphabet letter is a question?

Why do you find that most of the buildings are deprived of the 13th floor?

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

How many times do a clock's hands overlap in a day ?

If all Goats are Sheep and all Sheep are Deers, are all Deers Goats ?

Intelligence Agency need to break the vault but the problem is that they are not able to break the vault.

On the vault, a text is written as:

31 11 33 33 43 45
21 25
31 24 11 31 51 41

To Break the code Intelligence Agency brings a mathematician named Joseph.
Minutes later he deciphers the code.

Whats the code?

An exterior architect is asked by a builder to plant seven trees in a manner that there are exactly six rows of trees in a straight line and each row has three trees in particular.

How will he do it?

I cannot talk, but I always reply when spoken to. What am I?