Two cars A and B drive towards each other from places A and B at the same time. Car A travels 55 kilometers per hour, and car B travels 50 kilometers per hour. The two cars meet at a distance of 20 kilometers from the midpoint. How many kilometers is the distance.
甲乙两辆汽车同时从A、B两地相向开出，甲车每小时行55千米，乙车每小时行50千米，两车在离中点20千米处相遇，A、B两地的距离是多少千米．
<gadget id="calculator">55 + 50</gadget>
<output>105</output>

<gadget id="calculator">55 - 50</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20 * (2/5)</gadget>
<output>8</output>

<gadget id="calculator">105 * 8</gadget>
<output>840</output>

<result>840</result>