Can you start the fire using two pieces of wood?

Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

Find the missing number in the image below.

Two friends were stuck in a cottage. They had nothing to do and thus they started playing cards. Suddenly the power went off and Friend 1 inverted the position of 15 cards in the normal deck of 52 cards and shuffled it. Now he asked Friend 2 to divide the cards into two piles (need not be equal) with equal number of cards facing up. The room was quite dark and Friend 2 could not see the cards. He thinks for a while and then divides the cards in two piles.

On checking, the count of cards facing up is same in both the piles. How could Friend 2 have done it ?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

My location can be determined by the below rebus.
So where am i ?

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

If your uncle’s sister is not your aunt, what relation is she to you?