Calculation: (2/7)-(1/14)=how much.
计算：(2/7)-(1/14)=多少．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 / 14</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">(2/7) - (1/14)</gadget>
<output>3/14 = around 0.214286</output>

<result>3/14 = around 0.214286</result>