A job has been completed (4/7), how much is left.
一件工作，已经完成(4/7)，还剩下多少．
<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>