A and B start from A and B at the same time and walk towards each other, and they can meet each other within 4 hours. If both of them travel 1.8km less per hour, it will take 6 hours to meet each other. How many kilometers are there between A and B?
甲、乙两人分别从A、B两地同时出发相向而行，4小时可以相遇．如果两人每小时都少行1.8km，那么要6小时才能相遇．A、B两地相距多少千米？
<gadget id="calculator">1.8 * 2 * 6</gadget>
<output>21.6</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">21.6 / 2</gadget>
<output>10.8</output>

<gadget id="calculator">10.8 * 4</gadget>
<output>43.2</output>

<result>43.2</result>