A={1,2,3,4,5,5},B={2,3,5,7} then n(A-B)?

In this question, A represents a set of six elements, {1, 2, 3, 4, 5, 5}, and B represents a set of four elements, {2, 3, 5, 7}.

To find the set difference between A and B, we need to remove all the elements in B from A.

So, n(A-B) represents the number of elements in the set A that are not present in the set B.

Here, the set difference A-B can be written as {1, 4}. Therefore, n(A-B) = 2.

So, the answer to the question is n(A-B) = 2.