A pile of cement is transported away (1/4) for the first time and (2/5) for the second time. The first time transported 6 tons less than the second time. How many tons is this pile of cement? What is the correct column
一堆水泥，第一次运走(1/4)，第二次运走(2/5)，第一次比第二次少运6吨，这堆水泥原有多少吨？列式正确的是多少
<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>