Two masters and apprentices process a batch of parts. It takes 10 days for the master to do it alone, and 15 days for the apprentice to do it alone. How many hours does it take for the master and apprentice to process at the same time to complete the task?
师徒两人加工一批零件，师傅单独做需要10天，徒弟单独做需要15天，师徒两人同时加工需要多少小时完成任务？
<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>