The Wangcun production team wanted to dig a canal. On the first day, they dug the full length (1/4), and on the second day, they dug the full length (2/5). They dug a total of 390 meters in two days. How many meters have not been dug?
王村生产队要挖一条水渠，第一天挖了全长的(1/4)，第二天挖了全长的(2/5)，两天共挖了390米，这条水渠还有多少米没挖？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/4) + (2/5)</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">390 / (13/20)</gadget>
<output>600</output>

<gadget id="calculator">600 - 390</gadget>
<output>210</output>

<result>210</result>