Cristina was born in 1888. She just had her 30th birthday today how did that happen?

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 ?

John walks into the daily grocery shop and steals a $100 bill from the shop. An hour later John returns to the shop and buys some daily products for $40. John pays the owner the $100 bill and therefore the owner returns him $60.

How much money did the owner lose?

A boy purchased a book from a bookkeeper and gave him $100.
The cost of the book is $50 but the bookkeeper has no change, so he gets the change from the next shop and returns the boy his $50.

After some time the next shopkeeper came with the $100 note and told the bookkeeper that the note was a fraud, so he took the money back.

How much loss did the bookkeeper face?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

I was speeding and ran through a stop sign, yet two traffic officers who were there do nothing about it.

why?

Why despite killing dozens of people Charley and Wilma were not punished?

I start and end with 500 and carry a 5 in my heart. But I require the first letter and the first number to be complete. I am the name of a King.

Who am I ?

By moving just one matchstick, you need to make the below statement true. Can you do it?

What number do you get when you multiply all of the numbers on a telephone's number pad?