A pile of coal is used up (2/5), and there are still 75 tons left. How many tons is there in this pile of coal?
一堆煤，用去(2/5)，还剩75吨，这堆煤原来有多少吨？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">75 / (3/5)</gadget>
<output>125</output>

<result>125</result>