There are two circles, the sum of their areas is 18 square centimeters, the ratio of the circumference of the larger circle to the circumference of the smaller circle is 3:1, what is the area of the larger circle in square centimeters?
有两个圆，它们的面积之和为18平方厘米，大圆的周长与小圆周长的比是3：1，大圆的面积是多少平方厘米．
<gadget id="calculator">9 / 1</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">18 * (9/10)</gadget>
<output>81/5 = around 16.2</output>

<result>81/5 = around 16.2</result>