Answer:
public class Grade { 
    
    public static void main (String [] args) { 
        
        int sum = 0, avg = 0;
        char grade = 'x';
        Scanner input = new Scanner(System.in);
        
        System.out.print("Enter the test scores: ");
        for(int i=1; i<=3; i++) {
            int testScore = input.nextInt();
            sum += testScore;
        }
        
        avg = sum/3;
        
        if(avg >= 90) {
           grade = 'A'; 
        }
        else if(avg>= 80 && avg < 90) {
           grade = 'B'; 
        }
        else if(avg>= 70 && avg < 80) {
           grade = 'C'; 
        }
        else if(avg>= 60 && avg < 70) {
           
           System.out.print("Enter the number of homeworks turned in: ");
           int homeworksTurnedIn = input.nextInt();
           System.out.print("Enter the total number of homeworks: ");
           int totalHomeworks = input.nextInt();
           
           if((homeworksTurnedIn / (double)totalHomeworks) > 0.8) {
               grade = 'D';
           }
           else 
               grade = 'F';
        }
        else if(avg < 60) {
           grade = 'F'; 
        }
        
        System.out.println("Your grade is: " + grade);
    }
}
Explanation:
- Initialize the variables
- Ask the user for the test scores
- Inside the for loop, calculate the <em>sum</em> of the test scores
- Then, find the <em>average</em> of the scores
- Depending on the <em>average</em>, print the <em>grade</em>