Cars A and B start from two places at the same time and drive toward each other. Car A travels 40 kilometers per hour, and Car B travels 60 kilometers per hour. After 3 hours, they meet each other. How many kilometers are the distance between the two places?
甲、乙两车从两地同时出发相向而行，甲车每小时行40千米，乙车每小时行60千米，经过3小时相遇．两地相距多少千米？
<gadget id="calculator">40 + 60</gadget>
<output>100</output>

<gadget id="calculator">100 * 4</gadget>
<output>400</output>

<result>400</result>