There are three kinds of fruit trees in the orchard, pear trees account for 2/9 of the total number, peach trees account for 3/7 of the total number, and the rest are apple trees. What percentage of the total number of apple trees?
果园里有三种果树，梨树的棵数占总棵数的(2/9)，桃树的棵数占总棵数的(3/7)，其余的是苹果树．苹果树占总棵数的几分之几？
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

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

<gadget id="calculator">1 - (2/9) - (2/7)</gadget>
<output>31/63 = around 0.492063</output>

<result>31/63 = around 0.492063</result>