(6/7)-(6/7)*((2/3)+(1/9)).
(6/7)-(6/7)*((2/3)+(1/9))．
<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

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

<gadget id="calculator">(2/3) + (1/9)</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">(6/7) * (7/9)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(6/7) - (2/3)</gadget>
<output>4/21 = around 0.190476</output>

<result>4/21 = around 0.190476</result>