It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

I have no life, but I can die. What am I?

John is found dead in a bare field. Nobody killed John,
John did not commit suicide.

Inspector Jacob found a bag just a few meters away from John which could save his life. What was in the bag?

In the image below, can you find the value of an angle(y)

Jigsaw captured 100 people and make them stand in a circle and all these people are labelled as Person1, Person2, Person3... Person100. He made them play a crazy game in which Person 1 shot Person 2 and pass the gun to the next person and so on until one stands alive.

Which person will survive in the end?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

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

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

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 gave half of the apples he had plus one more to Jacob. He gave half of the remaining ones plus one more to James. Now, John was left with just one apple.

Can you find out how many did he have in the beginning?