There is a project to lay a 400km long cable line. 25% of the total length was laid in the first week, and 2/5 of the full length was laid in the second week. How many kilometers are left unpaved?
有一项工程要铺设一条400km长的电缆线，第一周铺设了全长的25%，第二周铺设了全长的(2/5)，还剩下多少千米没有铺？
<gadget id="calculator">25 / 100</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>

<gadget id="calculator">400 * (7/20)</gadget>
<output>140</output>

<result>140</result>