Write a function called LetterGrade. The input to this function is a single number, n. This funciton will return a string 'A','B','C','D', or 'F', corresponding to a grade of n, according to the following rule:

90-100 = A, 80-89.999 = B, 70-79.999 = C, 65-69.999 = D, 0-64.999 = F. If n is either less than 0 or greater than 100, the function will return the string 'error'.

Math lab homework, please help thank you so much.