What does this mathematical rebus means ?

Can you tell a 3D object that has just two surfaces?

I can be cracked, made, told, and played. What am I?

A King wants to send the diamond ring to his girlfriend securely. He got multiple locks and their corresponding keys. His girlfriend does not have any keys to these locks and if he sends the key without a lock, the key can be copied in the way. How can King send the ring to his girlfriend securely?

Solve the following series:
AZ, GT, MN, __, YB

There’s a one-story house in which everything is yellow. Yellow walls, yellow doors, yellow furniture. What colour are the stairs?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

John was gifted a new Hayabusa. He drove x miles at 55mph. Then he drove x+20 miles at 40mps. He drove his bike for 100 minutes. How much distance did he travel?

Can you circle exactly four of these numbers such that the total is twelve?

1 6 1
6 1 6
1 6 1
6 1 6

Move four matchsticks to the below square to form three squares?