Xiaoxiao read (2/5) of one book, but I didn't read the rest of this book.
笑笑看了一本书的(2/5)，还剩这本书的多少没看．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>