A road is a kilometer long. On the first day, 1/4 of the total length was repaired, and on the second day, 20% of the total length was repaired. The remaining kilometers were not repaired.
一条路长a千米，第一天修了全长的(1/4)，第二天修了全长的20%，剩下多少千米没修．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

<result>11/20 = around 0.55</result>