Question 45444
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
,n(A)=35,
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
if n(B)=x...then 
n(A u B)=35+x-12...since 12 are common to both A and B..hence
48=35+x-12
x=48+12-35=25
n(B)=25

 Find n(B). My answer is 13 but I'm not sure. Thanks for checking.