For a pile of coal, 1/4 of it was transported away for the first time, and 40% of it was transported away for the second time, leaving 35 tons. How many tons is this pile of coal?
一堆煤，第一次运走了它的(1/4)，第二次运走它的40%，还剩35吨．这堆煤原有多少吨？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">1 - (1/4) - (2/5)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">35 / (7/20)</gadget>
<output>100</output>

<result>100</result>