The binding team assembled a batch of books. It was originally planned to bind 240 volumes per day, and it took 15 days to complete the task; in reality, it bound 60 more volumes per day, and how many days did it take to complete the task?
装订小组装一批图书，原计划每天装订240册，15天完成；实际每天多装订60册，实际几天完成任务？
<gadget id="calculator">240 * 15</gadget>
<output>3_600</output>

<gadget id="calculator">240 + 60</gadget>
<output>300</output>

<gadget id="calculator">3_600 / 300</gadget>
<output>12</output>

<result>12</result>