A and B work together to do a job. Due to the good cooperation, A's work efficiency is 1/10 higher than that of doing it alone, and B's work efficiency is 1/5 higher than that of doing it alone. A and B work together for 6 hours and complete 2/5 of the whole work. On the second day, B worked alone for another 6 hours, leaving 13/30 of the work still to be completed. If this work is always done by A alone, how many hours will it take?
甲、乙合做一件工作，由于配合得好，甲的工作效率比单独做时提高1/10，乙的工作效率比单独做时提高1/5．甲、乙两人合做6小时，完成全部工作的2/5．第二天乙又单独做了6小时，还留下这件工作的13/30尚位完成．如果这件工作始终由甲一人单独来做，需要多少小时？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 6</gadget>
<output>1/15 = around 0.066667</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">(1/36) * (6/5)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/15) - (1/30)</gadget>
<output>1/30 = around 0.033333</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">(1/30) / (11/10)</gadget>
<output>1/33 = around 0.030303</output>

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

<result>33</result>