Question

Sets and probability
Suppose n(A upside down U B)=5, n(A U B)=35, and n(A)=12 What is n(B)?

Answer 1

\(n(A\cup B)=n(A)+n(B)-n(A\cap B)\)
\(35=12+n(B)-5\)
\(n(B)=28\).