There is a pile of 20 tons of sand on the construction site, 1/5 of the total amount is transported away on the first day, and 40% is transported away on the second day, how many tons are left?
工地有一堆沙20吨，第一天运走总数的(1/5)，第二天运走40%，还剩多少吨？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (1/5) - (2/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20 * (2/5)</gadget>
<output>8</output>

<result>8</result>