To build a road, when the full length (4/7) is built, it has exceeded the midpoint of 200 meters, how many kilometers is the total length of this road?
修一条路，当修完全长的(4/7)时，已超过中点200米，这条公路全长多少千米．
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(4/7) - (1/2)</gadget>
<output>1/14 = around 0.071429</output>

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

<result>2_800</result>