What does this rebus puzzle means ?

What does the below rebus puzzle mean?

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

That attorney is my brother, testified the accountant.

But the attorney testified he didn't have a brother.

Who is lying?

In a school, 280 students studied chemistry, 254 students studied physics and 280 students studied biology.

97 students studied chemistry as well as physics, 138 students studied physics as well as biology and 152 students studied chemistry as well as biology.

73 students studied all the three branches.

Can you find out the total number of students?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

As a whole I am both
safe and secure.

Behead me and I become
a place of meeting.

Behead me again and I am
the partner of ready.

Restore me, and I become
the domain of beasts.

What am I?

You are stuck with a gangster who likes to play it rough. The only way to survive is to accept his invitation to play Russian Roulette.

He presents a revolver in which, three bullets have been placed consecutively. Now he spins the chamber cylinder of the gun. The cylinder won't be spun again. The gun will be passed between both of you till the gun fires and one of you is dead.

Would you prefer to go first or second if you are given a choice?

Prove that the below maths equation is true.

8 + 8 = 91

'S' refers to the number of seconds in a day and 'H' refers to the number of hours in ten years. Which quantity out of these two is greater?