A book has been read (3/5), and the number of pages that have not been read is the number of this book.
一本书已看了(3/5)，没有看的页数是这本数的多少．
<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>

<result>2/5 = around 0.4</result>