An express train and a slow train depart from A and B respectively at the same time. The express train travels 75 kilometers per hour, and the slow train travels 65 kilometers per hour. The two trains meet at a distance of 20 kilometers from the midpoint. What is the distance between A and B in kilometers?
一列快车和一列慢车，分别从甲、乙两地同时相对开出，快车每小时行75千米，慢车每小时行65千米，两车在距中点20千米处相遇．甲、乙两地相距多少千米．
<gadget id="calculator">65 + 75</gadget>
<output>140</output>

<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">75 - 65</gadget>
<output>10</output>

<gadget id="calculator">40 / 10</gadget>
<output>4</output>

<gadget id="calculator">140 * 4</gadget>
<output>560</output>

<result>560</result>