Ships A and B depart from ports A and B at the same time and travel towards each other. It was the first time they met at a place 90 kilometers away from Port A. After the encounter, the two ships continue to move forward, return immediately after arriving at the destination, and meet for the second time at a distance of 10 kilometers from port A. How many miles is the distance between ports A and B?
甲、乙两船从A、B两港口同时出发相向而行．第一次在距A港90千米处相遇．相遇后两船继续前行，各自到达目的地后立即返回，在距A港10千米处第二次相遇．A、B两港口相距多少千米？
<gadget id="calculator">90 * 3</gadget>
<output>270</output>

<gadget id="calculator">270 + 10</gadget>
<output>280</output>

<gadget id="calculator">280 / 2</gadget>
<output>140</output>

<result>140</result>