1. The problem states: "B is a set of days of the week that starts with A." We need to understand what this means. 2. The days of the week are: Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday. 3. None of these days start with the letter A. 4. Therefore, the set B, defined as days of the week starting with A, is an empty set. 5. In set notation, we write this as $$B = \emptyset$$. 6. This means there are no elements in B because no day of the week starts with A.