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If n(a) = 35 and n(b)=8 find the following if the sets A and B are disjoint:
a) n (A intersect B)
b) N (a union B)
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a) In my understanding, if the sets A and B are disjoint, then their intersection is empty.
Hence, "if the sets A and B are disjoint", then n ( A intersect B) = 0 independently of numbers n(A), n(B).
b) n (A union B) = n(A) + n(B) = 35 + 8 = 42. (since the sets A and B are disjoint)