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For sets A and B, n(A union B) = 48
that is there are in all 48 elements in both A and B sets,counting repeat/common items once only
that is there are 35 elements in A
and n(A intersection B)=12.
that is there are 12 elements common to both A and B
n(A u B)=35+x-12...since 12 are common to both A and B..hence
Find n(B). My answer is 13 but I'm not sure. Thanks for checking.