Set Theoryhard
0:00.0

Let S={1,2,3,4,5,6,7}S = \{1, 2, 3, 4, 5, 6, 7\}. How many subsets ASA \subseteq S have the property that the intersection A{1,2,3}A \cap \{1, 2, 3\} has an odd cardinality?