When the numerator of (4/5) is enlarged by 3 times, how much should be added to the denominator, and the size of the fraction remains unchanged.
把(4/5)的分子扩大3倍，分母要加上多少，分数的大小不变．
<gadget id="calculator">15 - 5</gadget>
<output>10</output>

<result>10</result>