pile of 100 tons of coal, (1/5) of it is removed for the first time, (1/4) of it is removed for the second time, the same amount is removed for the third time as the second time, and the remaining What fraction of the coal is this pile of coal?
一堆煤100吨，第一次运走它的(1/5)，第二次运走它的(1/4)，第三次运走的与第二次运走的同样多，剩下的煤是这堆煤的几分之几？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(1/5) + (1/4) + (1/5)</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">1 - (13/20)</gadget>
<output>7/20 = around 0.35</output>

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