makaka

using System;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        private static int x = 0;
        private static int y = 0;
        private static int rightAnswer = 0;
        private static int bal = 0;
        private static int step = 1;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            GenerateUrav(ref x, ref y, ref rightAnswer);
        }

        private void GenerateUrav(ref int x, ref int y, ref int right)
        {
            Random random = new Random();
            x = random.Next(1,21);
            y = random.Next(1,21);
            right = x + y;
            label1.Text = $"{x} + {y} = ";
        }

        private void button1_Click(object sender, EventArgs e)
        {
            step++;

            if (step <= 5)
            {
                label2.Text = $"{step}/5";

                if (textBox1.Text != "")
                {
                    if (textBox1.Text == rightAnswer.ToString())
                    {
                        MessageBox.Show("Правильно!");
                        bal++;
                    }
                    else
                    {
                        MessageBox.Show("Неправильно!");
                    }
                }
                else
                {
                    MessageBox.Show("Неправильный ввод!");
                }
            }
            else
            {
                if (bal == 5)
                    MessageBox.Show("Отлично!");
                else if (bal == 4)
                    MessageBox.Show("Хорошо!");
                else if(bal == 3)
                    MessageBox.Show("Удовлетворительно");
                else
                    MessageBox.Show("Плохо");
                bal = 0;
                step = 1;
                label2.Text = $"{step}/5";
            }
            GenerateUrav(ref x, ref y, ref rightAnswer);
        }
    }
}