Add 3.2 to the former term of 8:15, in order to keep the obtained ratio unchanged, how much should be added to the latter term of the ratio.
把8：15的前项加上3.2，为了要使所得的比值不变，比的后项应加上多少．
<gadget id="calculator">21 - 15</gadget>
<output>6</output>

<result>6</result>