If X and Y are two sets such that X has 40 elements, `X uuY`has 60 elements and `X nnY`has 10 elements, how many elements does Y have?

Explanation

To solve the problem, we can use the formula for the number of elements in the union of two sets. The formula is:

\[ |X \cup Y| = |X| + |Y| - |X \cap Y| \]

Where:
- \( |X \cup Y| \) is the number of elements in the union of sets X and Y.
- \( |X| \) is the number of elements in set X.
- \( |Y| \) is the number of elements in set Y (which we need to find).
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