The two masters and apprentices cooperate to produce a batch of parts, and the task can be completed in 6 days. The master worked for 5 days first, then went out due to business, and the apprentice continued to work for 3 days, and the task was completed (7/10). If the master does it alone, how many days can the task be completed.
师徒二人合作生产一批零件，6天可以完成任务．师傅先做5天，因事外出，由徒弟接着做3天，共完成任务的(7/10)．如果师傅单独做，多少天可以完成任务．
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 / 6</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">(7/10) - (1/2)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">2 / (1/5)</gadget>
<output>10</output>

<result>10</result>