Eight of us go fourth, not back, to protect our king from an attack. What are we?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?

The ages of a father and son add up to 66.
The father's age is the son's age reversed.
How old could they be?
(3 possible solutions).

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?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

What has a bottom at the top?

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

Find three whole, positive numbers that have the same answer when multiplied together as when added together.