Part ADerek has $80 to spend on used books. Hardcover books cost $10 each, and paperbacks cost $20 each. Complete the equation which determines the number x of hardcover books and the number y of paperback books he can buy. x + y = Part BFor the situation in Part A, which of the following represent possible combinations of books that Derek can buy? Select all that apply.A. (0, 4)B. (2, 3)C. (7, 2)D. (8, 0)