As shown in the picture, the gold medal used in Beijing Olympic Games has a diameter of 70mm, the diameter of the center circle is 30mm, and the width of the gold medal's border is 5mm. Can you calculate the area of the ring-shaped jade wall inlaid on the back of the medal?

As shown in the picture, the gold medal used in Beijing Olympic Games has a diameter of 70mm, the diameter of the center circle is 30mm, and the width of the gold medal's border is 5mm. Can you calculate the area of the ring-shaped jade wall inlaid on the back of the medal?

The radius of the outer circle is (70-5 × 2) × 2 = 30 (mm), the radius of the inner circle is 30 ／ 2 = 15 (mm), so the area of the annular jade is: 3.14 × (302-152) = 3.14 × (900-225) = 3.14 × 675 = 2119.5 (mm). A: the area of the annular jade is 2119.5 mm