# Number of subsets

Discrete Mathematics Level pending

Let $$a$$ and $$b$$ be the elements of the two sets $$A$$ and $$B,$$ respectively. Find the number of ordered pairs $$( a, b )$$ when $$A$$ and $$B$$ satisfy the following two conditions:

$$1.$$ Both $$A$$ and $$B$$ are subsets of the set $$\left\{1,3, 5,7,9,11\right\}.$$
$$2.$$ $$A - B = \left\{ 1, 3, 5 \right\} .$$

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