The diameter of the small circle is equal to the radius of the large circle. The sum of the areas of the two circles is 45 square centimeters. What is the area of the large circle in square centimeters?
小圆的直径相当于大圆的半径，这两个圆的面积和是45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">1 + 4</gadget>
<output>5</output>

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

<gadget id="calculator">45 * (4/5)</gadget>
<output>36</output>

<result>36</result>