The road repair team builds a road. It is known that the ratio of the finished part to the total length is 1:3. If another 100 meters are repaired, then exactly 50% of the total length will be repaired. How long is this road in meters?
修路队修一条路，已知修完的与全长的比是1：3，如果再修100米，那么正好修全长的50%，这条路全长多少米？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">100 / (1/6)</gadget>
<output>600</output>

<result>600</result>