When building a road, when it reaches the full length (3/7), there is still 200 meters away from the midpoint of the road. How long is the road in meters?
修一条路，当修到全长的(3/7)时，距离这条路的中点还有200米，这条路全长多少米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(1/2) - (3/7)</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">200 / (1/14)</gadget>
<output>2_800</output>

<result>2_800</result>