Given code has compliation error C#:

Solution.cs(91,21): error CS0019: Operator '+' cannot be applied to operands of type 'string' and 'void'

Please fix it, we cannot edit these code. thanks!

If this is your first time with cpp classes I recommend you these 2 videos:

Constructor video

Inheritance video

For constructors with inheritance you can do something like this:

child (dataType inheritedParam1, dataType Param2) : father (inheritedParam1) {
	m_variable = Param2;
}

import java.util.Scanner;

class Person { String firstName; String lastName; int id;

public Person(String firstName, String lastName, int id) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.id = id;
}

}

class Student extends Person { private int[] testScores;

public Student(String firstName, String lastName, int id, int[] testScores) {
    super(firstName, lastName, id);
    this.testScores = testScores;
}

public char calculate() {
    int sum = 0;
    for (int score : testScores) {
        sum += score;
    }
    int avg = sum / testScores.length;

    if (avg >= 90) return 'O';
    else if (avg >= 80) return 'E';
    else if (avg >= 70) return 'A';
    else if (avg >= 55) return 'P';
    else if (avg >= 40) return 'D';
    else return 'T';
}

}

public class Solution { public static void main(String[] args) { Scanner scn = new Scanner(System.in); String firstName = scn.next(); String lastName = scn.next(); int id = scn.nextInt(); int numScores = scn.nextInt(); int[] scores = new int[numScores];

    for (int i = 0; i < numScores; i++) {
        scores[i] = scn.nextInt();
    }

    Student std = new Student(firstName, lastName, id, scores);
    System.out.println("Name: "+lastName+", "+firstName);
    System.out.println("ID: "+id);
    System.out.println("Grade: "+std.calculate());
    scn.close();
}

}

String calculate(){ int sum=0; for(int a:testScores){ sum+=a; } int avg=sum/testScores.length; if(avg>40){ if(avg<55) return "D"; if(avg<70) return "P"; if(avg<80) return "A"; if(avg<90) return "E"; else return "O"; } else{ return "T"; } }

Python Code: This is my solution:

class Person:
	def __init__(self, firstName, lastName, idNumber):
		self.firstName = firstName
		self.lastName = lastName
		self.idNumber = idNumber
	def printPerson(self):
		print("Name:", self.lastName + ",", self.firstName)
		print("ID:", self.idNumber)
		
class Student(Person):
    #   Class Constructor
    #   
    #   Parameters:
    #   firstName - A string denoting the Person's first name.
    #   lastName - A string denoting the Person's last name.
    #   id - An integer denoting the Person's ID number.
    #   scores - An array of integers denoting the Person's test scores.
    #
    # Write your constructor here
    def __init__(self, firstName, lastName, idNumber, scores):
        Person.__init__(self, firstName, lastName, idNumber)
        self.scores = scores
        

    #   Function Name: calculate
    #   Return: A character denoting the grade.
    #
    # Write your function here
    def calculate(self):
        average = sum(self.scores)/ len(self.scores)
        letter = '' "
        
        if average < 40:
            letter = 'T'
        elif 40 <= average < 55:
            letter = 'D'
        elif 55 <= average < 70:
            letter = 'P'
        elif 70 <= average < 80:
            letter = 'A'
        elif 80 <= average < 90:
            letter = 'E'
        elif 90 <= average <= 100:
            letter = 'O'
        return(letter)
        

line = input().split()
firstName = line[0]
lastName = line[1]
idNum = line[2]
numScores = int(input()) # not needed for Python
scores = list( map(int, input().split()) )
s = Student(firstName, lastName, idNum, scores)
s.printPerson()
print("Grade:", s.calculate())