define a function adjustgrade() that takes two parameters: total: an integer, passed by value, for the student's score. grade: a char, passed by reference, for the student's letter grade. adjustgrade() changes grade to a if the total is greater than or equal to 87 and less than or equal to 100, and grade is not a. otherwise, grade is not changed. the function returns true if grade has changed, and returns false otherwise. ex: if the input is 87 b, then the output is: grade is a after curving.