A poplar tree is the willow (2/9), and a poplar tree is the sum of poplar and willow.
杨树棵树是柳树的(2/9)，杨树棵树是杨树和柳树之和的多少．
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">1 + (2/9)</gadget>
<output>11/9 = around 1.222222</output>

<gadget id="calculator">(2/9) / (11/9)</gadget>
<output>2/11 = around 0.181818</output>

<result>2/11 = around 0.181818</result>