2: Add 6 to the former term of 3, if the ratio remains unchanged, how much should be added to the latter term of the ratio
2：3的前项加上6，要便比值不变，比的后项应该加上多少
<gadget id="calculator">2 + 6</gadget>
<output>8</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

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

<gadget id="calculator">12 - 3</gadget>
<output>9</output>

<result>9</result>