A project is to be done alone. A needs 10 days to complete, and B takes 15 days to complete. At the beginning, the two work together for 3 days. Due to work needs, A transfers away halfway, and the rest will be completed by B alone in how many days?
一项工程，单独做，甲要10天完成，乙要15天完成，开始二人一起干了3天，因工作需要甲中途调走，剩下的由乙独做一共用了几天完成？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) + (1/15)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/6) * 3</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) / (1/15)</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>