A and B start from two places at the same time and walk toward each other. A walks 6 kilometers per hour, 2 kilometers more than B per hour. The two meet after 3 hours. Find the distance in kilometers between the two places.
甲、乙两人分别从两地同时出发相向而行，甲每小时走6千米，比乙每小时多行2千米，两人经过3小时相遇．求两地相距多少千米．
<gadget id="calculator">6 - 2</gadget>
<output>4</output>

<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<result>30</result>