In a circle, the diameter of the outer circle is twice the diameter of the inner circle, and the area of the circle is 90 square centimeters, what is the area of the outer circle in square centimetres?
在一个圆环中，外圆直径是内圆直径的2倍，其中圆环的面积是90平方厘米，那么外圆的面积是多少平方厘米．
<gadget id="calculator">4 * 30</gadget>
<output>120</output>

<result>120</result>