For a pile of coal, its (1/4) is transported away for the first time, and its (2/5) is transported away for the second time. The first time transported 6 tons less than the second time. How many tons is this pile of coal?
一堆煤，第一次运走它的(1/4)，第二次运走它的(2/5)，第一次比第二次少运6吨．这堆煤原有多少吨？
<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">(2/5) - (1/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">6 / (3/20)</gadget>
<output>40</output>

<result>40</result>