The radius of the larger circle is equal to the diameter of the smaller circle. The sum of the areas of the two circles is 100 square centimeters. What is the area of the larger circle in square centimetres?
大圆的半径相当于小圆的直径，这两个圆的面积和是100平方厘米，大圆的面积是多少平方厘米．
<gadget id="calculator">4 / 1</gadget>
<output>4</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">100 * (4/5)</gadget>
<output>80</output>

<result>80</result>