A rope (3/4) meters, such as cutting off its (2/7), leaving its ((())/(())); if cutting off (2/7) meters, how much is left rice.
一根绳(3/4)米，如剪去它的(2/7)，还剩它的((())/(()))；如剪去(2/7)米，还剩多少米．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(3/4) - (2/7)</gadget>
<output>13/28 = around 0.464286</output>

<result>13/28 = around 0.464286</result>