The difference between the numerator and denominator of a fraction is 1. If 1 is subtracted from the numerator and 1 is added to the denominator, the value of the fraction is (4/5). What is the original fraction?
一个分数的分子，分母相差1，如果分子减去1，分母加上1，分数值是(4/5)，原分数是多少．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 + 1 + (4/5)</gadget>
<output>14/5 = around 2.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(14/5) / (1/5)</gadget>
<output>14</output>

<gadget id="calculator">14 - 1</gadget>
<output>13</output>

<gadget id="calculator">13 / 14</gadget>
<output>13/14 = around 0.928571</output>

<result>13/14 = around 0.928571</result>