How do I pass these variables to calculate a new GPA in my class?

sorry for this very similar question to my last post, but I'm having a slightly different problem to my last question. I have gotten everything to compile and work in my project, but I am not sure how to calculate a new gpa for student1 and student2 in my class by passing a total amount of points and a total amount of classes. My teacher wants us to calculate student1's gpa by passing 40 total points for 7 classes and to calculate student2's gpa by passing 36 total points for 8 classes. Like I said, the rest of my code works, I'm just not sure how to do this yet as I'm still fairly new to coding. The answer is probably pretty simple, but I can't figure it out for the life of me. Here is my code:

public class student
{
   private String name;
   private int year;
   private int age;
   private double gpa;
   /*
    * Default Constructor
    */
   public student()
   {
       name = "John";
       year = 2016;
       age = 16;
       gpa = 4.0;
   }
   /* 
    * other constructor
    */
   public student(String name, int year, int age, double gpa)
   {
       this.name = name;
       this.year = year;
       this.age = age;
       this.gpa = gpa;
   }
   /*
    * accessors
    */
   public String getName()
   {
       return name; 
   }
   public int getAge()
   {
       return age;
   }
   public int getYear()
   {
       return year;
   }
   public double getGpa()
   {
       return gpa;
   }
   /*
    * mutators
    */
   public void setName(String name)
   {
       this.name=name;
   }
   public void setGpa(double gpa)
   {
       this.gpa=gpa;
   }
   public void setYear(int year)
   {
       this.year=year;
   }
   public void setAge(int age)
   {
       this.age=age;
   }
   /*
    * calculate GPA
    */
   public double calcGpa(double points, int classes)
   {
      gpa = points / classes;       
      return gpa; 
   }
   public String toString() 
   {
    return name + year + age + gpa;
   }
}



public class studentReal
    {
       public static void main(String[] args)
       {
           student student1= new student("Jackie Java", 2018, 16, 4.7);
           student student2= new student("John Java", 2019, 15, 3.8);
           student student3= new student();
           System.out.println(student1.getName() + ", class " + student1.getYear()+ ", " + student1.getAge() + ", " + student1.getGpa());
           System.out.println(student2.getName() + ", class " + student2.getYear()+ ", " + student2.getAge() + ", " + student2.getGpa());
           System.out.println(student3.getName() + ", class " + student3.getYear()+ ", " + student3.getAge() + ", " + student3.getGpa());
       }
    }