The road repair team builds a road. The ratio of the repaired to the unrepaired is 1:3. After another 300 meters have been repaired, the repaired accounted for (1/2) of the road. How long is the road?
修路队修一条公路，已修的和未修的比是1：3，又修了300米后，已修的占这条路的(1/2)，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 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">300 / (1/4)</gadget>
<output>1_200</output>

<result>1_200</result>