Add 12 to the numerator of (3/8), how much should be added to the denominator to keep the size of the fraction constant
把(3/8)的分子加上12，要使分数的大小不变，分母应加上多少
<gadget id="calculator">3 + 12</gadget>
<output>15</output>

<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<gadget id="calculator">40 - 8</gadget>
<output>32</output>

<result>32</result>