In 3:8, if 1.5 is added to the former term, how much should be added to the latter term to keep the ratio unchanged.
在3：8中，如果前项加上1.5，要使比值不变，后项应加上多少．
<gadget id="calculator">3 + 1.5</gadget>
<output>4.5</output>

<gadget id="calculator">4.5 / 3</gadget>
<output>1.5</output>

<gadget id="calculator">8 * 1.5</gadget>
<output>12</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<result>4</result>