After a basket of fruit is sold (4/7), how much of this basket of fruit is left.
一筐水果卖了(4/7)后，还剩这筐水果的多少．
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>