When building a road, when it reaches the full length (2/7), there is still 210 meters away from the midpoint of the road. How long is the road in meters?
修一条公路，当修到全长的(2/7)时，距离这条路的中点还有210米，这条公路全长多少米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(1/2) - (2/7)</gadget>
<output>3/14 = around 0.214286</output>

<gadget id="calculator">210 / (3/14)</gadget>
<output>980</output>

<result>980</result>