using System;

public class Program

{

    public static void Main()

    {

        for (int i = 1; i < 10; i++)

        {

            var c = RandomCalculation(1, 2, 3, 4);

            Console.WriteLine(c.Text + ": " + c.Result);

        }

    }

    private static Random rnd = new Random();

​

    private class Operation

    {

        public readonly Func<int, int, int> Calculate;

        public readonly string Operator;

        public Operation(Func<int, int, int> calculate, string op)

        {

            Calculate = calculate;

            Operator = op;

        }

    }

​

    private static Operation Add = new Operation((a, b) => (a + b), "+");

    private static Operation Subtract = new Operation((a, b) => (a - b), "-");

    private static (int Result, string Text) RandomCalculation(int a, int b, int c, int d)

    {

        var abOperation = (rnd.Next(2) == 1) ? Add : Subtract;

        var cdOperation = (rnd.Next(2) == 1) ? Add : Subtract;

        return (

            (int)Math.Pow(abOperation.Calculate(a, b), 2) * cdOperation.Calculate(c, d),

            $"(a{abOperation.Operator}b)²*c{cdOperation.Operator}d");

    }

}