A pile of coal, used up (3/4), left ((())/(())).
一堆煤，用去了(3/4)，还剩((())/(()))．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>