An engineering team built a road. In the first week, 25% of the total length was repaired. In the second phase, 1/5 of the total length was repaired. The second phase was 3.5 kilometers shorter than the first phase. What is the total length of this road? km?
某工程队修一条公路，第一周修了全长的25%，第二期修了全长的(1/5)，第二期比第一期少修3.5千米，这条公路全长是多少千米？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">(1/4) - (1/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">3.5 / (1/20)</gadget>
<output>70</output>

<result>70</result>