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

Solve the equation by replacing the alphabet with numbers.

MOM + MOM + NO = BOOK=

What is black when you buy it, red when you use it, and gray when you throw it away?

What is the centre of gravity?

What does below chemistry rebus means?

Decode below rebus
D
N
A
T
S , D

Rectify the following equality 101 - 102 = 1 by moving just one digit.

You have an empty wine bottle with a cork that has been secured at the top in a normal way. There is a metal ring inside the bottle that is suspended by a string.

How can you make the metal ring drop to the bottom if you are not allowed to touch anything - not the bottle, not the cork, not the thread and not the ring?

How do you go from 98 to 720 using just one letter?

Two old friends, Jack and Bill, meet after a long time.

Three kids
Jack: Hey, how are you, man?
Bill: Not bad, got married and I have three kids now.
Jack: That's awesome. How old are they?
Bill: The product of their ages is 72 and the sum of their ages is the same as your birth date.
Jack: Cool..But I still don't know.
Bill: My eldest kid just started taking piano lessons.
Jack: Oh, now I get it.

How old are Bill's kids?