Cars A and B are traveling opposite each other at different speeds from cities A and B at the same time. On the way, they meet for the first time at a location 75 kilometers away from city A. After the meeting, the two cars continue to move forward at the same speed. The car returned immediately, and met for the second time on the way. At this time, the place where they met was 55 kilometers away from city B. How many kilometers are the distance between A and B cities?
甲、乙两辆汽车分别以不同速度同时从A、B两城相对而行，在途中第一次相遇地点距A城75千米，相遇后两车继续以原速前进，到达目的地后两车立即返回，在途中又第二次相遇，这时相遇的地点距B城55千米，AB两城相距多少千米．
<gadget id="calculator">75 * 3</gadget>
<output>225</output>

<gadget id="calculator">225 - 55</gadget>
<output>170</output>

<result>170</result>