If 15 is added to the numerator of (5/14), how much should the denominator be multiplied to keep the size of the fraction unchanged.
如果把(5/14)的分子加上15，要使分数的大小不变，分母应乘多少．
<gadget id="calculator">5 + 15</gadget>
<output>20</output>

<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<result>4</result>