A road repair team needs to repair a section of road. On the first day, it repaired (1/5) kilometers, and on the second day, it repaired (1/7) kilometers. In two days, it happened to repair (1/10) of this section of road. This section of road How many kilometers long?
某修路队需要修一段公路，第一天修了(1/5)千米，第二天修了(1/7)千米，两天正好修了这段公路的(1/10)，这段公路长多少千米？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/5) + (1/7)</gadget>
<output>12/35 = around 0.342857</output>

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

<gadget id="calculator">(12/35) / (1/10)</gadget>
<output>24/7 = around 3.428571</output>

<result>24/7 = around 3.428571</result>