When reading a book, the ratio of the number of pages read to the number of unread pages is 5:7, and how much of the book has been read.
读一本书，已读页数和未读页数的比是5：7，已读了全书的多少．
<gadget id="calculator">5 + 7</gadget>
<output>12</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<result>5/12 = around 0.416667</result>