canal was dug in two weeks. In the first week, 40% of the total length was dug, which was 120 meters less than in the second week. How many meters is this canal in total?
挖一条水渠两周挖完，第一周挖了全长的40%，比第二周少挖了120米，这条水渠共有多少米．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">120 / (1/5)</gadget>
<output>600</output>

<result>600</result>