Answer
books that are either in the warehouse in California or not Sci Fi books
$175,000$
Work Step by Step
$C\cup S'$ is the set of books that are either in the warehouse in California or not Sci Fi books
$n(C\cup S')=n(C)+n(S')−n(C\cap S')=(42,000)+(200,000-33,000)-(12,000+6,000+16,000)=42,000+167,000-34,000=175,000$