Question 1147276
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            In the post by @greenestamps,  the first line is not correct.


            So,  I came to bring the correct solution.



<pre>
(A U B U C) &#8745 (A U B' U C) = ((A\ (A &#8745 B)) U (C\ (C &#8745 B)).


((A\ (A &#8745 B)) U (C\ (C &#8745 B)) &#8745 (A U C)' = &#8709;


Here the sign  " \ " denotes the difference of a subset and its sub-subset.
</pre>


Solved.