Add 6 to the numerator of (3/5), how much should be added to the denominator to keep the fraction size unchanged
(3/5)的分子加上6，要使分数大小不变，分母应加上多少
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">15 - 5</gadget>
<output>10</output>

<result>10</result>