If n(U)=500, n(A)=150, n(B)=300 and n(A∩B)=70, then what is the value of n(A-B)

Question

n(A∩B)

Answer 1

∩ First, write out the definition of A-B.

 

A-B = A ∩ (¬ B)

The number of items in ...

A ... 150

A ∩ B ... 70

the elements in  A ∩ (¬ B) are the elements of A after you remove the elements in A ∩ B, so subtract the two numbers to get the answer.