If X and Y are two sets such that X Y has 18 elements, X has 8 elements and Y has 15 elements; how many elements does X Y have?


Given-


n(X) = 8, n(Y) = 15, and n(X Y) = 18


We know that-


n(X Y) = n(X)+ n(Y) - n(X Y)


18 = 8+15 - n(X Y)


18 = 23 - n(X Y)


n(X Y) = 23-18


n(X Y) = 5


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