Answer
n(C$\cup$N)=45
Work Step by Step
C$\cap$N is the set of authors who are successful and new.
C$\cup$N is the set of authors who are either successful or new.
n(C) = 30 (total of row 1)
n(N) = 20 (total of column 1)
n(C$\cap$N)= 5 (intersection of row 1 and column 1)
n(C$\cup$N)= (total successful = 30, which includes 5 new) + (15 new)
=45
n(C)+n(N)-n(C$\cap$N)=30+20-5=45 (verified)
