A project is completed in 12 days alone, and B is completed in 15 days alone. The two cooperate, and A leaves due to some business in the middle. Therefore, the task is completed in 12 days. How many days does A work less than B?
一项工程甲单独12天完成，乙单独15天完成，两人合作，中途甲因事离开，因此12天完成任务，求甲比乙少干几天？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) * 12</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/5) / (1/12)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>