public static void Main()
double sum, subtraction, product, division;
Console.WriteLine("The sum of " + a + " and " + b + " is: " +sum);
Console.WriteLine("The minus of " + d + " and " + b + " is: " +subtraction);
Console.WriteLine("The product of " + b + " and " + c + " is: " +product);
Console.WriteLine("The division of " + d + " by " + b + " is: " +division);
Console.WriteLine("The sum of " + c + " and " + d + " is: " +sum);