Two cars, passenger and freight, are traveling towards each other from places A and B at the same time. After 4 hours, the two cars meet. m, how many kilometers is the distance between A and B?
客、货两车同时从甲、乙两地相向而行，4小时后两车相遇，相遇时客、货两车所行的路程比是5：4，已知货车每小时比客车快15千米，甲乙两地相距多少千米？
<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">15 * 4 * 9</gadget>
<output>540</output>

<result>540</result>