If 21x = 79x, what is the value of x?

Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?

In the below-given picture of a pretty girl, there is something wrong. Can you find out what it is?

How many sides does a circle have?

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?

Can you move 2 matchsticks to form four equal sized squares.

I am a five-letter word and comprises two different vowels and three same consonants. I am so strong that I can spoil your entire work.

Can you find out who am I?

In case you were starting to feel confident, this one was meant for third graders in Vietnam. The answer is 66, but we don't blame you for scratching your head about how they got there.

Can you decipher these quotes by Albert Einstein?
Blf xzm mvevi hloev z kilyovn lm gsv ovevo lm dsrxs rg dzh xivzgvw.

What has lots of eyes, but can’t see?