Add 8 to the former term of 4:11, how much should the latter term be increased to keep the ratio unchanged.
把4：11的前项增加8，要使比值不变，后项应该增加多少．
<gadget id="calculator">8 + 4</gadget>
<output>12</output>

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

<gadget id="calculator">11 * 3</gadget>
<output>33</output>

<gadget id="calculator">33 - 11</gadget>
<output>22</output>

<result>22</result>