In 9:6, if the former term is reduced to 3, how much should the latter term be reduced to keep the ratio constant
在9：6中，如果前项减少到3，要使比值不变，后项应该减少多少
<gadget id="calculator">6 / 3</gadget>
<output>2</output>

<gadget id="calculator">6 - 2</gadget>
<output>4</output>

<result>4</result>