Team A and Team B rush to repair a section of the same length of railway at the same time. After 12 days of construction, the workload completed by the two teams is exactly equal to the total workload of team A. After 20 days of construction, team B has completed the task, and team A needs to repair another 400 meters to complete the task. How many meters is the total length of the two repaired railway sections?
甲乙两队同时各抢修一段同样长的铁路．开工12天后两队完成的工作量正好等于甲队的总工作量，开工20天后乙队完成了任务，甲队还需再修400米才能完成任务．两段抢修的铁路共长多少米．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 12</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">20 / 1</gadget>
<output>20</output>

<gadget id="calculator">(1/30) * 20</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">300 / (1/3)</gadget>
<output>900</output>

<gadget id="calculator">900 * 2</gadget>
<output>1_800</output>

<result>1_800</result>