DID I GET THIS CORRECT?

Following are the demand, total revenue, marginal revenue, total cost and marginal cost schedules (All in $) for a monopolist publisher of a textbook in Microeconomics. Number of Price Total Total Cost Marginal Marginal books per Revenue Cost hour Revenue 0 8 12 7 15 2 6 17 3 5 20 4 4 24 5 3 29 When the monopolist publisher maximizes its profits, what would be his total profit ($) per hour? Answer: 45