(2/9)-(1/6)=((())/(()))-((())/18)=how much.
(2/9)-(1/6)=((())/(()))-((())/18)=多少．
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(2/9) - (1/6)</gadget>
<output>1/18 = around 0.055556</output>

<result>1/18 = around 0.055556</result>