A vegetable field, (2/9) grows loofah, (4/9) grows tomatoes, how much of this land is left
一块菜地，(2/9)种丝瓜，(4/9)种西红柿，还剩这块地的多少
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 - (2/9) - (4/9)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>