and butte mere: SE 185, Spring 2020 One submission per group (2/3 students) 6. (60 points) Write a complete C program that uses a 2D array to store the assignment grades of two students (user input) and calculates each student's final grade by averaging the values. There should be four assignment grades per student and there should be two functions: one to calculate the average, another to determine the letter grade. The program must output the average grade and final letter grade in the following format: [submit the source code] Student 1 Avg = Student 1 Grade Student 2 Avg --- Student 2 Grade = Please use the following scale for the grade letter: A: 100-85 B: 84-75 C:74-60 F: 59-0 2 3