(4/21)/(2/7)-(1/27)/(1/9)=how much.
(4/21)/(2/7)-(1/27)/(1/9)=多少．
<gadget id="calculator">4 / 21</gadget>
<output>4/21 = around 0.190476</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(4/21) / (2/7)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 27</gadget>
<output>1/27 = around 0.037037</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(1/27) / (1/9)</gadget>
<output>1/3 = around 0.333333</output>

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

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