There is a pile of coal, (1/5) of it is removed on the first day, (1/4) of it is removed on the second day, and the same amount is removed on the third day as on the second day, and the rest is this pile of coal What fraction of?
有一堆煤，第一天运走它的(1/5)，第二天运走它的(1/4)，第三天运走的和第二天同样多，剩下的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) + (1/4)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>