(2/3) minus (1/6), and then minus (1/6)
(2/3)减去(1/6)，再减去(1/6)列式是多少
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

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

<gadget id="calculator">(2/3) - (1/6) - (1/6)</gadget>
<output>1/3 = around 0.333333</output>

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