For a pile of coal, the ratio of the tonnage transported to the total tonnage on the first day is 1:4, and after transporting 4.5 tons on the second day, exactly (2/3) of the total is transported away in two days. How many tons is this pile of coal?
一堆煤，第一天运走的吨数与总吨数的比是1：4，第二天运走4.5吨后，两天正好运走了总数的(2/3)．这堆煤共有多少吨？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/3) - (1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">4.5 / (5/12)</gadget>
<output>10.8</output>

<result>10.8</result>