Cars A and B start from places A and B at the same time and drive toward each other. Car A travels 40 kilometers per hour, and car B travels 60 kilometers per hour. After the two cars arrive at B and A respectively, they return immediately. When returning, the speed of car A increases by 1/2, and the speed of car B remains unchanged. It is known that the distance between two places where two cars meet twice is 50 kilometers, then how many kilometers is the distance between A and B?
甲、乙两车分别从A，B两地同时出发相向而行，甲车每小时行40千米，乙车每小时行60千米．两车分别到达B地和A地后，立即返回．返回时，甲车的速度增加二分之一，乙车的速度不变．已知两车两次相遇处的距离是50千米，则A，B两地的距离为多少千米．
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">40 / 60</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / (2/3)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) - 1</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) / 2</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(3/5) - (1/4)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">50 / (7/20)</gadget>
<output>1_000/7 = around 142.857143</output>

<result>1_000/7 = around 142.857143</result>