In an orchard, peach trees account for (1/7), pear trees account for (2/7), and the rest are apple trees. What percentage are apple trees?
一个果园，桃树占(1/7)，梨树占(2/7)，剩下的都是苹果树，苹果树占几分之几？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (1/7) - (2/7)</gadget>
<output>4/7 = around 0.571429</output>

<result>4/7 = around 0.571429</result>