If the ratio of two numbers is 3:4, when adding 12 to the previous term, to keep the ratio unchanged, how much should be added to the latter term
若两个数的比是3：4，当前项加上12时，要使比值不变，那么后项应加上多少
<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<result>16</result>