A fraction, if one of its fractional units is added, the result is equal to 1. If one of its fractional units is subtracted, the result is equal to (7/9), what is the fraction.
一个分数，如果加上它的一个分数单位，结果就等于1．如果减去它的一个分数单位，结果就等于(7/9)，这个分数是多少．
<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">1 - (7/9)</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">(2/9) / 2</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">1 - (1/9)</gadget>
<output>8/9 = around 0.888889</output>

<result>8/9 = around 0.888889</result>