The difference between the numerator and the denominator of a fraction is 12, which is (3/7) after division. What is the original fraction?
一个分数的分子与分母的差为12，约分后是(3/7)，原分数是多少？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>