If n(A - B) = 30, n(B - A) = 20 and n(A ∩ B) = 10, find :

(i) n(A)

(ii) n(B)

(iii) n(A ∪ B)

If n(A - B) = 30, n(B - A) = 48 and n(A ∩ B) = 15, find n(A ∪ B).

If n(universal set) = 80 and n(A) = 50, then n(complement of set A) is :

1. 80

2. 50

3. 30

4. none of these

If A = {5, 8, 10} and empty set ϕ. Then ϕ - A is equal to :

1. A

2. ϕ

3. {0}

4. none of these