There are three people A, B, and C. A travels 3 kilometers per hour, B travels 4 kilometers per hour, and C travels 5 kilometers per hour. A starts from A, and B and C start from B at the same time. C returns immediately after meeting A, and meets B again. At this time, exactly 10 hours have passed since the departure time. What is the distance in kilometers between A and B?
有甲、乙、丙三人，甲每小时行3千米，乙每小时行4千米，丙每小时行5千米．甲从A地，乙、丙从B地同时相向出发．丙遇到甲后立即返回，再遇到乙，这时恰好从出发时间开始算经过了10小时．求A、B两地之间的距离是多少千米？
<gadget id="calculator">4 * 10</gadget>
<output>40</output>

<gadget id="calculator">5 * 10</gadget>
<output>50</output>

<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">40 + 5</gadget>
<output>45</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">45 / (4/7)</gadget>
<output>315/4 = around 78.75</output>

<result>315/4 = around 78.75</result>