Add 12 to the former term of 3:5, how much should be multiplied by the latter term to keep the ratio constant.
3：5的前项加上12，要使比值不变，后项应乘上多少．
<gadget id="calculator">3 + 12</gadget>
<output>15</output>

<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<result>5</result>