Two cars drive from point A to point B at the same time, the fast car travels 6 kilometers more per hour than the slow car. The express train passes through point C 30 minutes earlier than the slow train. When the slow train reaches point C, the express train travels another 30 kilometers to point B. How many kilometers are there between AB and AB?
两辆汽车从A地同时开往B地，快车比慢车每小时多行6千米．快车比慢车早30分通过途中C地，当慢车到达C地时，快车又行30千米到达B地．AB两地多少千米？
<gadget id="calculator">30 / 0.5</gadget>
<output>60</output>

<gadget id="calculator">30 / 6</gadget>
<output>5</output>

<gadget id="calculator">60 * 5</gadget>
<output>300</output>

<result>300</result>