An engineering team rushed to repair a section of railway. The first team repaired 25%, the second team repaired 210 meters, and the two teams repaired exactly 40% of the total length. How long is this railway?
某工程队抢修一段铁路，第一队修了25%，第二队修了210米，两队修的刚好是全长的40%．这段铁路长多少米？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/5) - (1/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">210 / (3/20)</gadget>
<output>1_400</output>

<result>1_400</result>