3: Add 6 to the former term of 10, if you want to keep the ratio unchanged, how much should you add to the latter term
3：10的前项加上6，如果要使比值不变，后项应该加上多少
<gadget id="calculator">3 + 6</gadget>
<output>9</output>

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

<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<gadget id="calculator">30 - 10</gadget>
<output>20</output>

<result>20</result>