There are three concentric circles, the ratio of their radii is 3:4:5, if the area of the large circle is 100 square centimeters, what is the area of the circle formed by the middle circle and the small circle in square centimeters
有三个同心圆，它们的半径之比是3：4：5，如果大圆的面积是100平方厘米，那么中圆与小圆所构成的圆环的面积是多少平方厘米
<gadget id="calculator">100 / 25</gadget>
<output>4</output>

<gadget id="calculator">4 * 16</gadget>
<output>64</output>

<gadget id="calculator">4 * 9</gadget>
<output>36</output>

<gadget id="calculator">64 - 36</gadget>
<output>28</output>

<result>28</result>