Add 8 to the denominator of (3/4), how much should be added to the numerator to keep the size of the original fraction unchanged.
把(3/4)的分母加上8，要使原分数的大小不变，分子应加上多少．
<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<result>6</result>