One project was originally planned to be done by 40 people and completed in 15 days. If it is to be completed 3 days in advance, how many people need to be added.
一件工程原计划40人做，15天完成．如果要提前3天完成，需要增加多少人．
<gadget id="calculator">40 * 15</gadget>
<output>600</output>

<gadget id="calculator">15 - 3</gadget>
<output>12</output>

<gadget id="calculator">600 / 12</gadget>
<output>50</output>

<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<result>10</result>