There is a flower bed on campus, in which the area of roses accounts for (1/5), the area of rhododendrons accounts for (1/4), and the rest are roses. The area of the rose ((())/(())).
校园里有一个花坛，其中月季花的面积占(1/5)，杜鹃花的面积占(1/4)，其余的是玫瑰花．玫瑰花的面积((())/(()))．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/5) - (1/4)</gadget>
<output>11/20 = around 0.55</output>

<result>11/20 = around 0.55</result>