Question

Let $A$ and $B$ be finite sets such that $n(A-B)=18,n(A\cap B)$ $=25$ and $n(A\cup B)=70$ Then $n(B)$ is equal to

• A. 52
• B. 25
• C. 27
• D. 43
• E. 45

Answer 1

Answer: (A)

$18+25+x=70$
$x=70-43$
$x=27$
$n(B)=27+25$
$=52$