<PRE><B>Question 1071040</B>
out of the families that have DS, 20 have both, so subtract them from the total to get 124 - 20 = 104.


out of the families that have WII, 20 have both, so subtract them from the total to get 186 - 20 = 166.


you now have 3 categories that are pure.


104 own DS only.
266 own WII only.
20 own both.


the total that own either a DS or a WII but not both are equal to 104 + 266 = 370.


you have to subtract 20 from each category because it is included in both.
it is included in DS and it is included in WII.








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