Grade Calculator: Create an Excel spreadsheet that calculates the letter grade for a given score. Your spreadsheet will include the following items: A named cell that will contain any valid score between 0 and 100. A cell that calculates and displays the letter grade for the score. The letter grade is based on standard grade assignments as shown. You will need to use a series of nested if functions to accomplish this task. You may need to refer to the Excel help on the "it" function. Be sure to organize and properly label your spreadsheet. You must display your grade calculating equation in some type of annotation. Be sure the grader can understand your work. 90 SA 5100 80 B