Calculate the area of the outer rectangle.

The length is 10 cm and the width is 6 cm.

$$\text{Area}_{\text{outer}} = 10 \text{ cm} \times 6 \text{ cm} = 60 \text{ cm}^2$$

The length is 6 cm and the width is 4 cm.

$$\text{Area}_{\text{inner}} = 6 \text{ cm} \times 4 \text{ cm} = 24 \text{ cm}^2$$

The shaded area is the area of the outer rectangle minus the area of the inner rectangle.

$$\text{Area}_{\text{shaded}} = \text{Area}_{\text{outer}} - \text{Area}_{\text{inner}} = 60 \text{ cm}^2 - 24 \text{ cm}^2 = \boxed{36 \text{ cm}^2}$$

The length is 12 cm and the width is 12 cm.

$$\text{Area}_{\text{rectangle}} = 12 \text{ cm} \times 12 \text{ cm} = 144 \text{ cm}^2$$

The diameter of the semicircle is 12 cm, so the radius is $r = \frac{12}{2} = 6$ cm.

$$\text{Area}_{\text{semicircle}} = \frac{1}{2} \pi r^2 = \frac{1}{2} \times 3.1 \times (6 \text{ cm})^2$$ $$\text{Area}_{\text{semicircle}} = \frac{1}{2} \times 3.1 \times 36 \text{ cm}^2 = 3.1 \times 18 \text{ cm}^2 = 55.8 \text{ cm}^2$$

The total shaded area is the sum of the rectangle's area and the semicircle's area.

$$\text{Area}_{\text{total shaded}} = \text{Area}_{\text{rectangle}} + \text{Area}_{\text{semicircle}} = 144 \text{ cm}^2 + 55.8 \text{ cm}^2 = \boxed{199.8 \text{ cm}^2}$$

The side length of the square is $4 \text{ cm} + 4 \text{ cm} = 8$ cm.

$$\text{Area}_{\text{square}} = (8 \text{ cm})^2 = 64 \text{ cm}^2$$

The radius of the quarter circle is 4 cm.

$$\text{Area}_{\text{quarter circle}} = \frac{1}{4} \pi r^2 = \frac{1}{4} \times 3.1 \times (4 \text{ cm})^2$$ $$\text{Area}_{\text{quarter circle}} = \frac{1}{4} \times 3.1 \times 16 \text{ cm}^2 = 3.1 \times 4 \text{ cm}^2 = 12.4 \text{ cm}^2$$

The shaded area is the area of the square minus the area of the quarter circle.

$$\text{Area}_{\text{shaded}} = \text{Area}_{\text{square}} - \text{Area}_{\text{quarter circle}} = 64 \text{ cm}^2 - 12.4 \text{ cm}^2 = \boxed{51.6 \text{ cm}^2}$$

The diameter of the outer circle is 20 cm, so the radius is $R = \frac{20}{2} = 10$ cm.

$$\text{Area}_{\text{outer}} = \pi R^2 = 3.1 \times (10 \text{ cm})^2$$ $$\text{Area}_{\text{outer}} = 3.1 \times 100 \text{ cm}^2 = 310 \text{ cm}^2$$

The diameter of the inner circle is 10 cm, so the radius is $r = \frac{10}{2} = 5$ cm.

$$\text{Area}_{\text{inner}} = \pi r^2 = 3.1 \times (5 \text{ cm})^2$$ $$\text{Area}_{\text{inner}} = 3.1 \times 25 \text{ cm}^2 = 77.5 \text{ cm}^2$$

The shaded area is the area of the outer circle minus the area of the inner circle.

$$\text{Area}_{\text{shaded}} = \text{Area}_{\text{outer}} - \text{Area}_{\text{inner}} = 310 \text{ cm}^2 - 77.5 \text{ cm}^2 = \boxed{232.5 \text{ cm}^2}$$