A batch of parts is equally divided between A and B for processing. It takes 10 days for A to complete his task, and 15 days for B to complete his task. If A and B work together to process this batch of parts, how many days will it take to complete.
一批零件平均分给甲乙二人加工，甲完成自己的任务要10天，乙完成自己的任务要15天，如果甲乙二人共同加工这批零件，需要多少天完成．
<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 / (1/6)</gadget>
<output>6</output>

<result>6</result>