In 4:3, if 6 is added to the latter term, how much should be added to the former term to keep the ratio constant.
在4：3中，如果后项加上6，要使比值不变，前项要加上多少．
<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">12 - 4</gadget>
<output>8</output>

<result>8</result>