A pile of coal, 60% of it is used for the first time, and the rest (3/4) is used for the second time, leaving 12 tons. How many tons is there in this pile of coal?
一堆煤，第一次用去它的60%，第二次用去余下的(3/4)，还剩下12吨，这堆煤有多少吨？
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(2/5) * (3/4)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/5) - (3/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">12 / (1/10)</gadget>
<output>120</output>

<result>120</result>