Two cars, A and B, start from A and B at the same time and drive toward each other. The two cars meet after 8 hours. It is known that A will take 15 hours to complete the journey, and B will travel 21 kilometers per hour. The distance between A and B How many kilometers is it?
甲乙两车分别从A、B两地同时出发相向而行，两车经过8小时相遇，已知甲车行完全程要15小时，乙车每小时行21千米，AB两地之间的距离是多少千米？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/8) - (1/15)</gadget>
<output>7/120 = around 0.058333</output>

<gadget id="calculator">21 / (7/120)</gadget>
<output>360</output>

<result>360</result>