65% of a book has been read, and how much is left unfinished.
一本书，读了65%，还剩下多少没有读完．
<gadget id="calculator">65 / 100</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">1 - (13/20)</gadget>
<output>7/20 = around 0.35</output>

<result>7/20 = around 0.35</result>