There are two kinds of fast and slow trains departing from A and B at the same time and traveling towards each other. We met on the way 6 hours later. It is known that the fast train travels 84 kilometers per hour, which is 12 kilometers longer than the slow train. How many kilometers are there between A and B?
有快、慢两种列车同时从A、B两城出发，相向而行．6小时后在途中相遇．已知快车每小时行驶84千米，比慢车每小时多行12千米．A、B两城相距多少千米？
<gadget id="calculator">84 - 12</gadget>
<output>72</output>

<gadget id="calculator">72 + 84</gadget>
<output>156</output>

<gadget id="calculator">156 * 6</gadget>
<output>936</output>

<result>936</result>