A road has been repaired (1/3) in a certain project, and it will reach the midpoint after repairing 400m. How long is this road in meters?
某工程对修建公路，已修好了(1/3)，再修400m就到达中点，这条公路长多少米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">400 / (1/6)</gadget>
<output>2_400</output>

<result>2_400</result>