2-meter-long rope, cut off the full length (3/7), what is the remaining full length.
一条2米长的绳子，剪去全长的(3/7)，还剩下全长的多少．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (3/7)</gadget>
<output>4/7 = around 0.571429</output>

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