To build a 2-kilometer long road, the whole journey (1/4) is completed in the first week, and the whole journey (2/5) is completed in the second week. What fraction of the whole journey is completed?
修一条2千米长的路，第一周完成了全程的(1/4)，第二周完成了全程的(2/5)，再修全程的几分之几就修完了这条路？
<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 - (1/4) - (2/5)</gadget>
<output>7/20 = around 0.35</output>

<result>7/20 = around 0.35</result>