The engineering team repaired a section of road, which has already repaired the full length (4/7), and there is still 840 meters to be repaired. How long is this road in meters?
工程队修一段公路，已经修了全长的(4/7)，还有840米没有修．这段公路全长多少米？
<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">840 / (3/7)</gadget>
<output>1_960</output>

<result>1_960</result>