The campus Bookstore at East Tennessee State University must decide now many economics textbooks to order for the next semester's class. The bookstore believes that either seven, eight, nine, or ten sections of the course will be offered next semester; each section contains 40 students.

The publisher is offering bookstores a discount if they place their order early. If the bookstore orders too few texts and run out, the publisher will air express additional book at the bookstore's expense. If it orders too many texts, the store can return unsold texts to the publisher for a partial credit. The bookstore is considering ordering either 280, 320, 360, or 400 texts in order to get discount. Taking into account the discounts, air express expenses and credits for return texts, the bookstore manager estimates the following resulting profits:

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