Cars A and B leave opposite places A and B respectively. The first meeting is 90 kilometers away from place A. After the meeting, the two cars continue to move forward at the same speed, and return immediately after reaching the destination. The second meeting is at At the 50th kilometer from B. What is the distance in kilometers between A and B?
甲、乙两车分别从A、B两地相对开出，第一次相遇离A地90千米，相遇后两车继续以原速前进，到达目的地后又立刻返回，第二次相遇在离B第50千米处．求A、B两地间相距多少千米？
<gadget id="calculator">90 * 3</gadget>
<output>270</output>

<gadget id="calculator">270 - 50</gadget>
<output>220</output>

<result>220</result>