Operator '<' cannot be applied to operands of type 'decimal' and 'double'

I'm trying to come up with a program that calculates grades given from the users input. I am also trying to set a limit on how high or low the user input can be (i.e 0 <= or >= 100). But when I use decimal it keeps giving me this error, "Operator '<' cannot be applied to operands of type 'decimal' and 'double'"

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Grade_Program
{
    class Program
    {
        static void Main(string[] args)
        {
            string First;
            string Last;
            First = "Cristiano";
            Last = " Ronaldo";
            Console.Write("Please enter student name <First Last>: ");
            Console.WriteLine(First + Last );

            Console.WriteLine(" ");

                                                     Console.WriteLine("*************NOTE**********************************************");
        Console.WriteLine("*** Be sure to include decimal point for scores.            ***");
        Console.WriteLine("***     !!!All score should range from 0.00 to 100.00 !!    ***");
        Console.WriteLine("***                                                         ***");
        Console.WriteLine("*** For example : 80.50                                     ***");
        Console.WriteLine("***************************************************************");

        Console.WriteLine(" ");

        decimal Exam_1;
        decimal Exam_2;
        decimal Exam_3;
        decimal Assignment_1;
        decimal Assignment_2;

        Console.Write("Please enter score for Exam 1 <Example: 100.0>: ");
        Exam_1 = Convert.ToDecimal(Console.ReadLine());

        if (Exam_1 < 0.0 | Exam_1 > 100.0)
            Console.Write("Exam score cannot be less than 0. or greater than                      100.0. Please re-enter the score for Exam 1 <Example: 95.0>:");
            Exam_1 = Convert.ToDecimal(Console.ReadLine());

        Console.Write("Please enter score for Exam 2 <Example: 0.0>: ");
        Exam_2 = Convert.ToDecimal(Console.ReadLine());