There is a bridge between A and B. A and B set off from A and B at the same time, and meet on the bridge 3 hours later. If A speeds up and travels 2 kilometers more per hour, and B starts 0.5 hours earlier, they will still meet on the bridge. How many kilometers are there between A and B?
A、B两地间有一座桥，甲、乙两人分别从A、B两地同时出发，3小时后在桥上相遇．如果甲加快速度，每小时多行2千米，而乙提前0.5小时出发，则仍旧在桥上相遇，如果甲延迟0.5小时出发，乙每小时少走2千米，还会在桥上相遇，则A、B两地相距多少千米？
<gadget id="calculator">3 - 0.5</gadget>
<output>2.5</output>

<gadget id="calculator">2.5 / 0.5</gadget>
<output>5</output>

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

<gadget id="calculator">3 + 0.5</gadget>
<output>3.5</output>

<gadget id="calculator">3.5 / 0.5</gadget>
<output>7</output>

<gadget id="calculator">2 * 7</gadget>
<output>14</output>

<gadget id="calculator">10 + 14</gadget>
<output>24</output>

<gadget id="calculator">24 * 3</gadget>
<output>72</output>

<result>72</result>