For a pile of coal, the ratio of the number of tons transported to the total tonnage on the first day is 1:3. After 4.5 tons were transported on the second day, half of the total was transported in two days. How many tons is there in this pile of coal?
一堆煤，第一天运走的吨数与总吨数的比是1：3，第二天运走4.5吨后，两天正好运走了总数的一半，这堆煤有多少吨？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">4.5 / (1/6)</gadget>
<output>27</output>

<result>27</result>