There are two piles of coal. The ratio of the coal stored in the first pile and the second pile is 12:7. After transporting away (1/4) from the first pile, the second pile is 2.4t less than the first pile. How many tons is a pile of original coal?
有两堆煤，原来第一堆和第二堆存煤量的比是12：7，从第一堆运走(1/4)后，这时第二堆比第一堆少2.4t，第一堆原有煤多少吨？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">12 * (3/4)</gadget>
<output>9</output>

<gadget id="calculator">9 - 7</gadget>
<output>2</output>

<gadget id="calculator">2.4 / 2</gadget>
<output>1.2</output>

<gadget id="calculator">1.2 * 12</gadget>
<output>14.4</output>

<result>14.4</result>