A book of fairy tales, read 24 pages a day, and finish it in 15 days. If you read 30 pages a day, how many days will it take to finish it?
一本童话故事书，每天看24页，15天看完，如果每天看30页，需几天看完？
<gadget id="calculator">15 / 30</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">24 * (1/2)</gadget>
<output>12</output>

<result>12</result>