Add 8 to the numerator of (2/5), how much should be added to the denominator to keep the size of this fraction unchanged.
把(2/5)的分子加上8，要使这个分数的大小不变，分母应该加上多少．
<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<gadget id="calculator">25 - 5</gadget>
<output>20</output>

<result>20</result>