Three different kinds of flowers are planted in a circular flowerbed. Among them, peonies account for (2/5) of the total area, lilies account for (1/10) of the total area, and the rest are roses. What percentage of the total area do roses occupy?
一个圆形花圃里种了3种不同的花．其中牡丹占总面积的(2/5)，百合占总面积的(1/10)，其余是玫瑰．玫瑰占总面积的几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (2/5) - (1/10)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>