To build a canal, the full length (3/5) has been repaired, and the unrepaired is how much has been repaired
修一条水渠，已经修了全长的(3/5)，未修的是已修的多少
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / (3/5)</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>