The numerator of (5/8) is increased by 15, how much should the denominator be increased to keep the size of the fraction constant.
(5/8)的分子增加15，要使分数的大小不变，分母应该增加多少．
<gadget id="calculator">8 * 4</gadget>
<output>32</output>

<gadget id="calculator">32 - 8</gadget>
<output>24</output>

<result>24</result>