A highway has been built for 60km, accounting for 1/7 of the total length. What is the total length of this highway in km?
一条公路已经修了60km，占全长的(1/7)，这条公路全长多少km．
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">60 / (1/7)</gadget>
<output>420</output>

<result>420</result>