Question

If A and B are two sets such that n(A-B)= 45 , n(B-A)=23 and n(A∩B)=9
Then find n(A), n(B) and n(A∪).​

Answer 1

Answer:

n (a-b)=20+x

n(b-a)=3x

n(a n b ) =x+1

we know that

n(a-b) =n (a) - n(a n b)

therefore n(a) = n(a-b) + n( a n b)

3x + ( x+1)

4x+1

according to the question

n (a) = n (b)

therefore 2x +21 = 20

therefore x = 10

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