To build a section of road, 300m was built for the first time, and then (1/4) was repaired, then the ratio of the repaired to the unrepaired is 2:1, find the total length.
修一段路，第一次修了300m，再修(1/4)，那么修的和未修的比是2：1，求全长．
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/3) - (1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">300 / (5/12)</gadget>
<output>720</output>

<result>720</result>