<PRE><B>Question 1042269</B>
I used a Venn diagram with 3 intersecting circles.
If I start with just the A and B circles alone and
allow them to intersect, the intersection has 10
cards in it. 
---------------
The part of circle A that is outside the intersection 
has 50 - 10 = 40 cards in it.
---------------
The part of circle B that is outside the intersection
has 25 - 10 = 15 cards in it
---------------
So far 40 + 10 + 15 = 65 cards are accounted for.
Now I slide the C circle into the intersection of
A and B. This doesn&#39;t change the results I already have.
---------------------------------------------
There are 100 cards total, so 100 - 65 = 35 
MUST be outside circles A and B
-------------------------------
35 cards have only the letter C and not A or B
--------------
Hope I got this right -you can get another opinion, too</PRE>