As shown in the figure, the radius of the small circle is 4dm, and the shadow part accounts for 1 / 5 of the area of the small circle and 1 / 8 of the area of the large circle. How many square decimeters is the area of the large circle

As shown in the figure, the radius of the small circle is 4dm, and the shadow part accounts for 1 / 5 of the area of the small circle and 1 / 8 of the area of the large circle. How many square decimeters is the area of the large circle

1 / 5 of small circle area: 3.14 × 4 × 4 × 1 / 5 = 10.048 square decimeters
Large circle area: 10.048 △ 1 / 8 = 80.384 square decimeters