Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

What has a ring but no finger?

Find the value of "a" by solving the maths equation in the picture below:

A thief enters a store and threatens the clerk, forcing her to open the safe. The clerk says, “The code for the safe is different every day, and if you hurt me you’ll never get the code.” But the thief manages to guess the code on his own. How did he do it?

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.

I can be made.
I can be cracked.
I can be told.
I can be played.

Who am I?

A family is trapped in a jungle. There is a bridge which can lead them to safety. But at one time, the bridge can only allow two people to pass through. Also, all of them are afraid of the dark and thus, they can't go alone.

Father takes 1 minute to cross, the mother takes 2 minutes, the son takes 4 and the daughter takes 5 minutes. While crossing the time taken will be according to the slower one. How can they all reach the other side in the minimum possible time?

Krish is 45 years old and his mother Crishtina is 73 years old.

Can you find out how many years ago, his mother was three times his age?