Add 16 to the denominator of (3/8), how much to add to the numerator, the size of the fraction remains the same.
(3/8)的分母加上16，分子要加上多少，分数的大小不变．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

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

<result>6</result>