The ratio of the areas of the two big and small circles is 25:4, and the sum of their circumferences is 21.98 cm. What is the difference between the areas of the two big and small circles?
大小两个圆的面积比是25：4，它们的周长之和是21.98厘米，大小两个圆的面积的差是多少．
<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">21.98 / 7</gadget>
<output>3.14</output>

<gadget id="calculator">2 / 3.14 / 2</gadget>
<output>0.318471</output>

<gadget id="calculator">3.14 * 0.318471</gadget>
<output>0.999999</output>

<gadget id="calculator">0.999999 ** 2</gadget>
<output>0.999998</output>

<gadget id="calculator">0.999998 / 4</gadget>
<output>0.25</output>

<gadget id="calculator">25 - 4</gadget>
<output>21</output>

<gadget id="calculator">3.14 * 0.25 * 21</gadget>
<output>16.485</output>

<result>16.485</result>