Hope the farm has an orchard, of which (1/4) are peach trees, (2/5) are pear trees, and the rest are orange trees. What percentage of the land are orange trees?
希望农场有一块果园，其中(1/4)是桃树，(2/5)是梨树，剩下的是橘子树．橘子树占这块地的几分之几？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

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