A novel, if you read 20 pages a day, you can finish it in 9 days. If you want to finish it in 6 days, how many more pages do you need to read every day?
一本小说，如果每天看20页，9天可看完，如果想6天看完，每天需多看多少页．
<gadget id="calculator">9 / 6</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">20 * (3/2)</gadget>
<output>30</output>

<gadget id="calculator">30 - 20</gadget>
<output>10</output>

<result>10</result>