Cars A and B start from A and B at the same time respectively, and travel between A and B continuously. The speed ratio of cars A and B is 3:7, and the 1996th and 1997th encounters between A and B are exactly 120 kilometers apart (Note: When A and B are in the same direction, Car B catching up with Car A is not counted as an encounter). So, what is the distance in kilometers between A and B?
甲、乙两车分别从A、B两地同时出发，在A、B两地之间不断往返行驶．甲、乙两车的速度比为3：7，并且甲、乙两车第1996次相遇的地点和第1997次相遇的地点恰好相距120千米(注：当甲、乙两车同向时，乙车追上甲车不算作相遇)．那么，A、B两地之间的距离是多少千米？
<gadget id="calculator">120 / 6</gadget>
<output>20</output>

<gadget id="calculator">20 * 10</gadget>
<output>200</output>

<result>200</result>