The ratio of the circumference of the large circle to the circumference of the small circle is 9:4. What is the area of the large circle equal to the area of the small circle?
大圆周长与小圆周长的比是9：4，大圆面积是小圆面积的多少
<gadget id="calculator">81 / 16</gadget>
<output>81/16 = around 5.0625</output>

<result>81/16 = around 5.0625</result>