Let n(U)=46 n (AUB)^1=20 n(A)=22 Find n(B-A)

Question

Have somewhat an idea of how to do this but not this complex. Any help would be great!

Answer 1

n(A U B) = n(U) - n(A U B)' = 46-20 = 26

But,

n(A U B) = n(A) + n(B-A)

=> n(B-A) = n(A U B) - n(A) = 26 - 22 = 4

 

Let me know if this makes sense. I can explain in detail otherwise. Thanks.