The road repairing team builds a road. The ratio of the length already repaired to the length not repaired is 1:3. If another 150 meters are repaired, 50% of the total length will be repaired. What is the total length of this road?
修路队修一条路，已经修的长度与未修的长度比是1：3，如果再修150米，则正好修完全长的50%，这条路全长是多少？
<gadget id="calculator">50 / 100</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">150 / (1/4)</gadget>
<output>600</output>

<result>600</result>