Answer:
f(−5)= −150, meaning if the company sells -5 shirts, they would make a profit of -150 dollars. This interpretation does NOT make sense in the context of the problem.
f(7)= −30, meaning if the company sells 77 shirts, they would make a profit of −30 dollars. This interpretation makes sense in the context of the problem.
f(10.5)= 5, meaning if the company sells 10.5 shirts, they would make a profit of 5 dollars. This interpretation does NOT make sense in the context of the problem.
Based on the observations above, it is clear that an appropriate domain for the function is whole numbers (0, 1, 2, ...).
(Yes, these answers are officially correct.)