For a book, the number of pages read is equivalent to unread (3/7), and there are still ((())/(())) of the whole book unread.
一本书，已看的页数相当于未看的(3/7)，还剩全书的((())/(()))未看．
<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<result>7/10 = around 0.7</result>