Shengli primary school selected students from grade four to grade six to take part in the math competition. Seven students are not in the fourth grade and 60 students are not in the fifth grade. How many students are in the fourth grade? What a strange question. I calculated that there are 4.5.6 students with x.y.z, 7 students who are not in the fourth grade, y+z=7, 60 students who are not in the fifth grade, and x+z=60. Divide 7 into 1, 6 2, 5 3, 4, and get many answers.