Add 16 to the former item of 8:15, how much should the latter item be increased to keep the ratio unchanged.
把8：15的前项增加16，要使比值不变，后项应增加多少．
<gadget id="calculator">8 + 16</gadget>
<output>24</output>

<gadget id="calculator">24 / 8</gadget>
<output>3</output>

<gadget id="calculator">3 * 15</gadget>
<output>45</output>

<gadget id="calculator">45 - 15</gadget>
<output>30</output>

<result>30</result>