If the numerator of (9/12) is reduced by 3 times, how much should the denominator be reduced to keep the size of the fraction constant.
把(9/12)的分子缩小3倍，要使分数的大小不变，分母应减少多少．
<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">12 - 4</gadget>
<output>8</output>

<result>8</result>