The numerator of (5/9) is enlarged to 20, how many times should the denominator be enlarged to keep the size of the fraction unchanged.
(5/9)的分子扩大到20，要使分数大小不变，分母要扩大多少倍．
<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<result>4</result>