Add 8 to the numerator of (4/5), how much should the denominator be multiplied to keep the fraction size unchanged?
(4/5)的分子加上8，要使分数大小不变，分母应该乘多少
<gadget id="calculator">4 + 8</gadget>
<output>12</output>

<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<result>3</result>