Let A and B be two sets such that: n (A) = 20, n (A ∪ B) = 42 and n (A ∩ B) = 4. Find n (A – B)
n (A – B)
We know,
n (A – B) = n (A ∪ B) – n (B)
Substituting the values we get
n (A – B) = 42 – 26
= 16
∴ n (A – B) = 16
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