Uncle Wang has a piece of open land, use this land for watermelons (2/5), plant bananas (1/4), and the rest for vegetables. What percentage of the land is planted with vegetables?
王大伯有块空地，种西瓜用去这块地的(2/5)，种香蕉用去这块地的(1/4)，其余的用来种青菜．种青菜的地占这块地的几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">1 - (2/5) - (1/4)</gadget>
<output>7/20 = around 0.35</output>

<result>7/20 = around 0.35</result>