What is the word or phrase?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

What does below rebus means ?

I know a nine-letter word having only one vowel.
Do you ?

How many letters are in the alphabet?

Identify the hidden meaning behind this picture?

In a town, there are over 100 flats.
Flat-1 is named first flat.
Flat-2 is named second flat.
Flat-3 is named third flat.

A visitors 'Victor' decides to walk through all the flats, he finds all the flats except flat-62.
Victor later founds that the local of the town have given it another name.

What is the name of the Flat?

If,

20 % 5 = 24

21 % 7 = 33

42 % 6 = 67

Then;

66 % 6 = ?

Which alphabet letter is a question?