After adding 9 to the former term of 3:8, how much should the latter term be multiplied to keep the ratio constant?
把3﹕8的前项加上9后，要使比值不变，后项应该乘多少
<gadget id="calculator">3 + 9</gadget>
<output>12</output>

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

<result>4</result>