The taxi fare standard in a certain city is: 9 yuan within 3 kilometers, and 2.5 yuan per kilometer for distances exceeding 3 kilometers. Xiaoying and her father took a taxi from home to the train station and paid a total of 21.5 yuan. How many kilometers is the distance from Xiaoying's house to the train station?
某市的出租车收费标准是：3千米以内一律9元，超出3千米的路程，每千米收费2.5元，小英和爸爸乘坐出租车从家去火车站，一共付车费21.5元，小英家到火车站的路程是多少千米？
<gadget id="calculator">21.5 - 9</gadget>
<output>12.5</output>

<gadget id="calculator">12.5 / 2.5</gadget>
<output>5</output>

<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<result>8</result>