The numerator of (2/9) is increased by 4, how much should the denominator be increased to keep the size of the fraction constant
(2/9)的分子增加4，要使分数的大小不变，分母应增加多少
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 * 9</gadget>
<output>18</output>

<result>18</result>