The engineering team is repairing a section of road. The ratio of the repaired to the unrepaired is 1:3. If another 500 meters are repaired, it will be just half completed. How long is this road in total?
工程队修一段路，目前已修的和未修的比是1：3，如果再修500米，就刚好修完一半，这条路共有多长？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 + 3</gadget>
<output>4</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">500 / (1/4)</gadget>
<output>2_000</output>

<result>2_000</result>