A canal has a total length of 400 meters. On the first day (1/5) of the entire project was completed, and another 120 meters was repaired on the second day. What fraction is left unrepaired?
一条水渠全长400米，第一天完成了全部工程的(1/5)，第二天又修了120米，还剩几分之几没有修？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">120 / 400</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (1/5) - (3/10)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>