A section of the road has already been repaired (2/5), and if another 300 meters is repaired, half of this section of the road can be repaired. What is the total length of this section of the road in meters?
一段公路已经修了它的(2/5)，再修300米，就能修好这段公路的一半，这段公路全长多少米．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 5</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">300 / (1/10)</gadget>
<output>3_000</output>

<result>3_000</result>