Solve the Problem $n ( B ) = 24 , n ( A \cap B ) = 5$

Multiple Choice

Solve the problem.
-If $n ( B ) = 24 , n ( A \cap B ) = 5$ , and $n ( A \cup B ) = 42$ , find $n ( A )$ .

A) 21
B) 18
C) 23
D) 25