Xiaolin and Xiaoqiang are walking towards each other from places A and B which are 22.5 kilometers apart at the same time. Xiaolin's speed is 2.5 kilometers per hour, and Xiaoqiang's speed is 3 kilometers per hour. In order to arrive on time, the two make an appointment At the location, Xiaolin started to set off 12 minutes earlier than Xiaoqiang. At the same time, the puppy brought by Xiaolin ran towards Xiaoqiang at a speed of 5 kilometers per hour. Xiaoqiang, the puppy ran to Xiaolin immediately after meeting Xiaoqiang...until Xiaolin and Xiaoqiang met, asking for the distance the puppy traveled.
小林和小强在同一时刻分别从相距22.5千米的甲‘乙两地相向而行，小林的速度为2.5千米/小时，小强的速度为3千米/小时，为了能按时到达两人约好的地点，小林比小强提前12分钟开始出发，同时小林所带的小狗以5千米/小时的速度奔向小强，小狗遇到小强后立即回头奔向小林，遇到小林后又奔向小强，小狗遇到小强后有立即奔向小林…直到小林和小强相遇，求小狗所走的路程．
<gadget id="calculator">2.5 * 0.2</gadget>
<output>0.5</output>

<gadget id="calculator">22.5 - 0.5</gadget>
<output>22</output>

<gadget id="calculator">2.5 + 3</gadget>
<output>5.5</output>

<gadget id="calculator">22 / 5.5</gadget>
<output>4</output>

<gadget id="calculator">4 + 0.2</gadget>
<output>4.2</output>

<gadget id="calculator">4.2 * 5</gadget>
<output>21</output>

<result>21</result>