1. **State the problem:** We need to find the area of a rectangle with sides labeled $x - 3$ and $x + 3$. 2. **Formula for area of a rectangle:** $$\text{Area} = \text{length} \times \text{width}$$ 3. **Apply the formula:** $$A = (x - 3)(x + 3)$$ 4. **Multiply the binomials using the distributive property (FOIL):** $$A = x \cdot x + x \cdot 3 - 3 \cdot x - 3 \cdot 3$$ 5. **Simplify each term:** $$A = x^2 + 3x - 3x - 9$$ 6. **Combine like terms:** $$A = x^2 + \cancel{3x} - \cancel{3x} - 9$$ 7. **Final simplified expression:** $$A = x^2 - 9$$ **Answer:** The area of the rectangle is $x^2 - 9$.