Add 16 to the denominator of (3/8), how much should be added to the numerator to keep the size of the fraction constant.
(3/8)的分母加上16，要使分数的大小不变，分子应该加上多少．
<gadget id="calculator">8 + 16</gadget>
<output>24</output>

<gadget id="calculator">24 / 8</gadget>
<output>3</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<result>6</result>