project can be completed in 12 days alone, and B can be completed in 15 days alone. After several days of cooperation, A is transferred away, and the rest of the project is completed by B alone. If the work efficiency of the company is increased by 25%, and it takes another 6 days to complete the rest of the project, then how many days A has worked less than B.
一项工程，甲单干12天可以完成，乙单干15天可以完成，两人合作若干天后，甲被调走，剩下的工程由乙独自完成，乙干了3天后，为了早点完工，将自己的工作效率提高了25%，又用了6天的时间完成了剩下的工程，则甲比乙少干了多少天．
<gadget id="calculator">3 + 6</gadget>
<output>9</output>

<result>9</result>