A project can be completed in 10 days alone, and B alone can be completed in 15 days. After A completes half of the project first, the remaining two teams will work together. How many days will it take to complete the task?
一项工程甲独做10天完成，乙独做15天完成，甲先做工程的一半后，剩下两队合做，还要多少天完成任务？
<gadget id="calculator">1 / 2</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 / 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">(1/2) / (1/6)</gadget>
<output>3</output>

<result>3</result>