Find area and perimeter of triangle by coordinates via c# operands?

Question

C++ / C#

1 is all in the console

class mymath
    {
        private mymath()
        { }
        public static int sum(int a, int b)
        {
            return a + b;
        }
        public static int sub(int a, int b)
        {
            return a - b;
        }
        public static int mul(int a, int b)
        {
            return a * b;
        }
        public static int div(int a, int b)
        {
            return a / b;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(mymath.sum(23, 78));
            Console.ReadKey();
        }
    }

something like such a solution like an operand created how to initialize x and y is not entirely clear

Answer 1

Operands are some quantities or variables in an expression.
Not quite, that is, it is not at all clear what is meant?
And what is "initiate x and y"?