Uncle Li has a vegetable field. He plans to use (2/7) of this field to grow cabbage, (1/5) to grow celery, and the rest to grow rapeseed. What percentage of the vegetable field is the rapeseed land?
李大伯有一块菜地，计划利用这块地的(2/7)种白菜，(1/5)种芹菜，其余的种油菜，种油菜的地占这块菜地的几分之几？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (2/7) - (1/5)</gadget>
<output>18/35 = around 0.514286</output>

<result>18/35 = around 0.514286</result>