Subtract 9 from the numerator of (18/36), how much should be subtracted from the denominator to keep the size of the fraction constant
(18/36)的分子减去9，要使分数的大小不变，分母应减去多少
<gadget id="calculator">36 / 18</gadget>
<output>2</output>

<gadget id="calculator">36 / 2</gadget>
<output>18</output>

<result>18</result>