There is a road that is being paved at a certain time and speed. When it reaches (3/4) of this road, the paving plan is changed, the paving speed is increased (1/8), and the daily paving time is reduced (1/ 3), as a result, it took 13 days to lay the road. Ask how many days the original plan was laid.
有一条马路正按一定时间和速度进行铺设，当铺设到这条马路的(3/4)时，改变了铺设计划，铺设速度增加了(1/8)，每天的铺设时间减少了(1/3)，结果铺设这条马路共用了13天．问原计划铺设多少天．
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 + (1/8)</gadget>
<output>9/8 = around 1.125</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(9/8) * (2/3)</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(1/4) / (3/4)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(3/4) + (1/3)</gadget>
<output>13/12 = around 1.083333</output>

<gadget id="calculator">13 / (13/12)</gadget>
<output>12</output>

<result>12</result>