1. **State the problem:** We need to find an expression for the area of the shaded region, which is the area of the circle minus the area of the rectangle inside it. 2. **Identify the given dimensions:** The rectangle inside the circle has width $3x$ and height $2y$. 3. **Write the formula for the area of the rectangle:** $$\text{Area}_{\text{rectangle}} = \text{width} \times \text{height} = 3x \times 2y = 6xy$$ 4. **Determine the radius of the circle:** The circle has a horizontal line labeled $3x$ extending from the center to the edge, which represents the radius $r = 3x$. 5. **Write the formula for the area of the circle:** $$\text{Area}_{\text{circle}} = \pi r^2 = \pi (3x)^2 = \pi \times 9x^2 = 9\pi x^2$$ 6. **Write the expression for the shaded area:** The shaded area is the area of the circle minus the area of the rectangle: $$\text{Area}_{\text{shaded}} = 9\pi x^2 - 6xy$$ 7. **Factor the expression:** Factor out the common term $3x$: $$9\pi x^2 - 6xy = 3x(3\pi x - 2y)$$ **Final answer:** $$\boxed{3x(3\pi x - 2y)}$$