Which word does the below Plexor means ?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

There is a shop where written:
Buy 1 for $1
10 for $2
100 for $3
I needed 999 and still only paid $3. How could this be financially viable for the shop-keeper?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

When it is alive we sing, when it is dead we clap our hands. What is it?

What work can one never finish?

I inserted a coin in a bottle and closed its mouth with the help of a cork. Now, I was able to take the coin out from the bottle without taking out the cork or breaking the bottle. Can you tell me how I did it?

A Club organizes a Running Race, and John, Jacob, Minda, and Tony participated.

The results are as follows

John beats Jacob
Minda beats Toni
Toni beats John

Who came first in the race?