Add 12 to the numerator of (4/15), how much should be added to the denominator if the size of the fraction is to remain the same
(4/15)的分子加上12，如果要使这个分数的大小不变，分母应该加上多少
<gadget id="calculator">60 - 15</gadget>
<output>45</output>

<result>45</result>