Two cars leave from A and B at the same time and drive towards each other. After 3 hours of departure, the distance between the two cars is 600 kilometers. After 9 hours of departure, the two cars meet. What is the distance in kilometers between A and B?
两辆汽车从甲、乙两地同时开出，相向而行，出发3小时后，两车相距600千米，出发9小时后，两车相遇，甲、乙两地相距多少千米．
<gadget id="calculator">600 / 6</gadget>
<output>100</output>

<gadget id="calculator">100 * 9</gadget>
<output>900</output>

<result>900</result>