In 3:12=6:24, if the second item increases by 6, how much does the fourth item increase before the ratio can be established.
在3：12=6：24中，如果第二项增加6，则第四项增加多少，比例才能成立．
<gadget id="calculator">12 + 6</gadget>
<output>18</output>

<gadget id="calculator">18 / 3</gadget>
<output>6</output>

<gadget id="calculator">6 * 6</gadget>
<output>36</output>

<gadget id="calculator">36 - 24</gadget>
<output>12</output>

<result>12</result>