The construction site transports 2 tons of yellow sand, use up (2/5) of it on the first day, and use up (1/4) of it on the second day, what fraction is left?
建筑工地运来2吨黄沙，第一天用去它的(2/5)，第二天用去它的(1/4)，还剩几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

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

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