The distance between Mary and Jack is 14 kilometers. Mary took the puppy and Jack from her home at the same time and walked towards each other. During the journey, the puppy met Jack and returned immediately. After meeting Mary, the puppy returned immediately. Until Mary meets Jack, if Mary’s walking speed is 3 kilometers per hour, Jack’s walking speed is 4 kilometers per hour, and the puppy’s speed is 10 kilometers per hour, then when Mary and Jack meet, the puppy runs away How many kilometers?
玛丽和杰克两家相距14千米，玛丽带了小狗与杰克同时从自己家里出发相向而行，在行进中，小狗与杰克相遇后，立即返回，小狗和玛丽相遇后，立即返回，直到玛丽与杰克相遇为止，若玛丽步行速度为每小时3千米，杰克步行速度为每小时4行米，小狗速度为每小时10千米，那么在玛丽和杰克相遇时，小狗跑了多少千米？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) * 3</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(1/10) * 4</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/10) + (2/5)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">14 / (7/10)</gadget>
<output>20</output>

<result>20</result>