In the ratio 3:4=6:8, if 4 is added to 4, how much should 3 be added to make the ratio still valid
在比例3：4=6：8中，如果4加上4，要使比例仍然成立，则3应加多少
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

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

<result>3</result>