7. The total number of shirts produced in an hour cannot exceed 1000. (E)
8. The total cost of producing dress shirts and casual shirts together cannot exceed $8400 per hour. (C)
9. The number of casual shirts produced per hour must be non-negative. (F)
10. The number of dress shirts produced per hour must be non-negative. (A)
Therefore, the correct matches are:
7. B
8. C
9. F
10. A