Two engineering teams, A and B, jointly build a section of road. A works alone for 4 days and completes (1/3) of this section of road. Later, B joins in. The two teams work together for 3 days to complete the construction task of this section of road, and B alone repairs it. How many days will it take to complete?
甲乙两工程队合修一段公路，甲先单独施工4天，完成这段公路的(1/3)，后来乙加入，两队合修3天，完成这段公路的修筑任务，问乙单独修需要几天完成？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) / 4</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) * 3</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/3) - (1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">(5/12) / 3</gadget>
<output>5/36 = around 0.138889</output>

<gadget id="calculator">1 / (5/36)</gadget>
<output>36/5 = around 7.2</output>

<result>36/5 = around 7.2</result>