Find the number of elements in the set A, if B has 36 elements and
n ( A ∩ B ) = 18, n (A U B )= 55.
n(A) = __
n( A ∩ B ) = n(A) + n(B) - n(A U B )
18 = n(A) + 36 - 55
take over
n ( A ∩ B ) = 18, n (A U B )= 55.
n(A) = __
18 = n(A) + 36 - 55
take over