(6/7)-(5/7)=how much.
(6/7)-(5/7)=多少．
<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">(6/7) - (5/7)</gadget>
<output>1/7 = around 0.142857</output>

<result>1/7 = around 0.142857</result>