The road repair team wants to build a road. 30% of the total length was repaired on the first day, the remaining 40% was repaired in the morning of the second day, and the rest (4/7) was repaired again in the afternoon. There is still 10km left. How many kilometers is this road?
修路队要修一条路．第一天修了全长的30%，第二天上午修了余下的40%，下午修了再次余下的(4/7)，还剩10km，这条路长多少千米？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(7/10) * (3/5) * (3/7)</gadget>
<output>9/50 = around 0.18</output>

<gadget id="calculator">10 / (9/50)</gadget>
<output>500/9 = around 55.555556</output>

<result>500/9 = around 55.555556</result>