To build a highway, the road construction team repaired 50 kilometers more (1/5) of the road in the first month, and 20 kilometers less than the total length (1/4) in the second month, and the result is still left 300 meters, how many kilometers is the total length of this expressway?
修建一条高速公路，修路队第一个月修了这条路的(1/5)多50千米，第二个月修的比全长的(1/4)少20千米，结果还剩余300米，这条高速公路全长多少千米？
<gadget id="calculator">50 - 20</gadget>
<output>30</output>

<gadget id="calculator">300 + 30</gadget>
<output>330</output>

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

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/4) - (1/5)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">330 / (11/20)</gadget>
<output>600</output>

<result>600</result>