For a section of road, the full-length (2/5) will be repaired in the first week, the first week (2/5) will be repaired in the second week, and the full-length ((())/(())) will be repaired in the second week.
一段路，第一周修全长的(2/5)，第二周修第一周(2/5)，第二周修全长的((())/(()))．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) * (2/5)</gadget>
<output>4/25 = around 0.16</output>

<result>4/25 = around 0.16</result>