Add 8 to the numerator of (4/15), how much should be added to the denominator if the size of this fraction is to remain the same
(4/15)的分子加上8，如果要使这个分数的大小不变，分母应该加上多少
<gadget id="calculator">4 + 8</gadget>
<output>12</output>

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

<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<gadget id="calculator">45 - 15</gadget>
<output>30</output>

<result>30</result>