Add 6 to the numerator of (6/7), how much should be added to the denominator to keep the size of the fraction unchanged
(6/7)的分子加上6，要让分数的大小不变，分母应加上多少
<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<gadget id="calculator">14 - 7</gadget>
<output>7</output>

<result>7</result>