The two masters and apprentices cooperate to complete a project. Due to the good cooperation, the master's work efficiency is increased (1/10) and the apprentice's work efficiency is increased (1/5). The two work together for 6 days to complete (2/5) of the entire project, and then the apprentice works alone for another 6 days. At this time, the project is still (13/30) unfinished. If the master does this project alone, it will take a few days Finish?
师徒两人合作完成一项工程，由于配合得好，师傅的工作效率比单独做时要提高(1/10)，徒弟的工作效率比单独做时提高(1/5)．两人合作6天，完成全部工程的(2/5)，接着徒弟又单独做6天，这时这项工程还有(13/30)未完成，如果这项工程由师傅一人做，几天完成？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">13 / 30</gadget>
<output>13/30 = around 0.433333</output>

<gadget id="calculator">1 - (2/5) - (13/30)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/6) / 6</gadget>
<output>1/36 = around 0.027778</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

<gadget id="calculator">(6/5) / (11/10)</gadget>
<output>12/11 = around 1.090909</output>

<gadget id="calculator">(1/36) * (12/11)</gadget>
<output>1/33 = around 0.030303</output>

<gadget id="calculator">1 / (1/33)</gadget>
<output>33</output>

<result>33</result>