The road repair team builds a road. The ratio of the number of meters that have been repaired to the number of meters that have not been repaired is 3:7. If another 6 meters are repaired, the full length (2/5) will be repaired. How long is this road?
修路队修一条公路，已修的米数和未修的米数比是3：7，如果再修6米，就修了全长的(2/5)，这条路有多长？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(2/5) - (3/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">6 / (1/10)</gadget>
<output>60</output>

<result>60</result>