The fractional value of a fraction is equal to (12/13), adding 3 to the numerator, the fraction is equal to the natural number 1, find the fraction.
一个分数的分数值等于(12/13)，分子加上3，这个分数就等于自然数1，求这个分数．
<gadget id="calculator">13 - 12</gadget>
<output>1</output>

<gadget id="calculator">3 / 1</gadget>
<output>3</output>

<gadget id="calculator">3 * 13</gadget>
<output>39</output>

<gadget id="calculator">12 / 39</gadget>
<output>4/13 = around 0.307692</output>

<gadget id="calculator">3 * (4/13)</gadget>
<output>12/13 = around 0.923077</output>

<result>12/13 = around 0.923077</result>