In a certain town, of each 100 men 85 are married, 70
have a telephone, 75 own a car, and 80 own their own
house.  Always on a base of 100 men, what is the least
possible number who are married, have a telephone, own
a car, and own their own house?
 
 

                THE SOLUTION

15 are not married, 30 do not have a telephone, 25 do
not have a car, 20 do not own their own house.  It is
possible that these 90 men are all different, which
would leave only 10 men with wife, phone, car, and house.