Random Riddle: Grandmothers Birthday

How old is your son? asked a man to his neighbour. My son is five times as old as my daughter and my wife is five times as old as my son. Iam twice as old as my wife whereas my grandmother, who is celebrating her eighty-first birthday is as old as all of us put together.

How old is the man’s son?
 

Random Riddle: Grandmothers Birthday