Add 10 to the numerator of (5/8), and how much to add to the denominator, the size of the fraction will remain the same.
(5/8)的分子加上10，分母加上多少，分数的大小才会不变．
<gadget id="calculator">5 + 10</gadget>
<output>15</output>

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

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

<gadget id="calculator">24 - 8</gadget>
<output>16</output>

<result>16</result>