1. The problem states: E is a set of quadrilaterals. 2. A quadrilateral is a polygon with four sides and four vertices. 3. The set E contains all shapes that have exactly four sides. 4. There is no specific question or operation given, so we understand E as the collection of all four-sided polygons. 5. Important properties of quadrilaterals include the sum of interior angles being $$360^\circ$$ and various types such as squares, rectangles, trapezoids, and rhombuses. 6. Without further instructions, the problem is simply defining the set E as all quadrilaterals.