In 3:5, if the latter term of the ratio is increased by 3, how much should the former term be increased to keep the ratio constant
在3：5中，如果比的后项增加3，要使比值不变，前项应增加多少
<gadget id="calculator">4.8 - 3</gadget>
<output>1.8</output>

<result>1.8</result>