The numerator of (3/5) is increased by 12, how much should the denominator be increased to keep the size of the fraction constant
(3/5)的分子增加12，要使分数的大小不变，分母应增加多少
<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<gadget id="calculator">3 + 12 + 1 + 4</gadget>
<output>20</output>

<result>20</result>