Math Problem #4

 What is the value of y?

Murder Mystery #2

A serial killer had a particular practice going:
He kidnapped people and made them take one of two pills.
One was harmless.
The other was poisonous.
Whichever pill a victim took, the serial killer took the other one.
Then the scheme repeated itself continuously: victims took their pills with water and died.
The killer repeatedly survived.

How did he always get the harmless pill, why didn't he die?

Enigma #2 - Jailbreak

John is placed in a cell with a dirt floor, and only one window (no bars) positioned so high that no one could reach it.
The cell is empty except for a shovel and John. It's hot and dry there but John won't get any food or drink anytime soon.
He only has 2 days to break out of the jail, if not, he will die.

Digging a tunnel is not an option as it will take more than two days...

How should John escape the cell?