A circular road with a width of 4 meters is paved around a circular lawn with a diameter of 18 meters. What is the area of the circular road?
在一个直径为18米的圆形草地周围铺一条宽4米的环形道路，求这条环形路的面积是多少？
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">9 + 4</gadget>
<output>13</output>

<gadget id="calculator">13 ** 2</gadget>
<output>169</output>

<gadget id="calculator">9 ** 2</gadget>
<output>81</output>

<gadget id="calculator">169 - 81</gadget>
<output>88</output>

<gadget id="calculator">3.14 * 88</gadget>
<output>276.32</output>

<result>276.32</result>