A road is 20 kilometers long, repaired (2/5) in the first week, and 25% in the second week, how many kilometers are left?
一条路长20千米，第一周修了(2/5)，第二周修了25%，还剩多少千米．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (2/5) - (1/4)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">20 * (7/20)</gadget>
<output>7</output>

<result>7</result>