40% of a road has been repaired, and if another 200 meters are repaired, half of the road can be repaired. How long is this road in meters?
一条公路已经修了它的40%，再修200米，就能修好这条路的一半．这条公路全长多少米？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">200 / (1/10)</gadget>
<output>2_000</output>

<result>2_000</result>