Sixth grade students go to the Martyrs Cemetery to receive revolutionary traditional education during the Ching Ming Festival. If you rent a 35-seat bus, you need 4 cars, and if you rent a 42-seat bus, you only need 3 cars. The number of groups is exactly equal to the number of people in each group, so how many students in this grade participated in this educational activity?
六年级学生在清明节期间，去烈士陵园接受革命传统教育，如果租35个座位的客车需要4辆，如果租42个座位的客车只需要3辆，到达烈士陵园后要求分组活动，且分得的组数跟每组的人数恰好相等，则此年级共有多少学生参加了此次教育活动？
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