A pile of coal burned (1/4) of the total amount on the first day, and 5.5 tons on the second day. At this time, what was not burned was burned (1/4). How many tons is this pile of coal?
一堆煤，第一天烧了总数的(1/4)，第二天烧了5.5吨，这时未烧的是已烧的(1/4)．这堆煤共有多少吨？
<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

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

<gadget id="calculator">(4/5) - (1/4)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">5.5 / (11/20)</gadget>
<output>10</output>

<result>10</result>