Bonus - проблем
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace _7.Bonus_Score
{
    class Program
    {
        static void Main(string[] args)
        {
            var score = int.Parse(Console.ReadLine());
            var bonus = 0.0;
            if (score <= 100)
            {
                bonus = bonus + 5;
            } else if (bonus <= 1000)
            {
                bonus = bonus + (score * 0.2);
            } else if (score > 1000)
            {
                bonus = bonus + (score * 0.1);
            }
            if (score % 2 == 0)
            {
                bonus = bonus + 1;
            }
            if (score % 10 == 5)
            {
                bonus = bonus + 2;
            }
            Console.WriteLine(bonus);
            Console.WriteLine(score + bonus);
        }
    }
}
{
bonus = bonus + 5;
}else if (score <= 1000)
{
bonus = bonus + (score * 0.2);
}else if (score > 1000)
{
bonus = bonus + (score * 0.1);
}