Ross, pp. 16-17, # 1, 3, 4, 5, 11, 12.
(A) Evaluate 9P3.
(B) Evaluate 7P4 / 5P4.
(C) Solve for r: 12 (7Pr) = 5 (9Pr). (You may find this one difficult.)
Please show your work. Please give your answers as numbers (e.g., 120 rather than 5!).