There is a pile of coal weighing (8/9) tons, and (5/9) tons are used up, how many tons are left?
有一堆煤重(8/9)吨，用去了(5/9)吨，还剩多少吨？
<gadget id="calculator">8 / 9</gadget>
<output>8/9 = around 0.888889</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">(8/9) - (5/9)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>