Class 61 of a certain school went on an autumn tour to Fangshan Mountain, which is 18 kilometers away. There was only one car, and they had to be divided into two groups, A and B. Group A takes the car first, and group B walks; when the car reaches A, group A gets off and walks, the car returns to pick up group B, and finally the two groups arrive at Fangshan at the same time. It is known that the car travels 60 kilometers per hour, and the students walk 4 kilometers per hour. May I ask: How many kilometers is the distance between A and Fangshan?
某学校六一班同学去18千米远的方山秋游，只有一辆汽车，需要分成甲乙两组．甲组先乘车，乙组步行；车行驶到A处时，甲组下车步行，汽车返回接乙组，最后两组同时到达方山．已知汽车每小时行驶60千米，学生每小时步行4千米．请问：A处与方山相距多少千米？
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