Reading a book, if you read 10 pages a day, you can finish it in 15 days; if you read 25 pages a day, how many days can you finish it in advance?
读一本书，如果每天读10页，15天可以读完，如果每天读25页，可以提前几天读完？
<gadget id="calculator">15 / 25</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">10 * (3/5)</gadget>
<output>6</output>

<gadget id="calculator">15 - 6</gadget>
<output>9</output>

<result>9</result>