project is done alone. A needs 12 days to complete, and B takes 15 days to complete. At first, the two work together. Because of work needs, A transfers away halfway, and B and B take 10 days to complete. How many days did Team A transfer away?
一项工程，单独做，甲要12天完成，乙要15天完成，开始二人一起干，因工作需要甲中途调走，结果乙一共用了10天完成．甲队中途调走了几天？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) * 10</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

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

<gadget id="calculator">(1/3) / (1/12)</gadget>
<output>4</output>

<gadget id="calculator">10 - 4</gadget>
<output>6</output>

<result>6</result>