Answer:
7 purchases and above makes it the better buy.
Explanation:
Plan B is $30 more than Plan A, but Plan A charges $5 per movie. 6 movies would cost $30, covering the difference between Plan B. So at 6 purchases the Plan's prices would even out, but Plan B would only become the better plan at 7 purchases. By the context of the question it is a bit hard to tell if you should answer 6, 7, and 8, or just 7 and 8, but it does say "better buy." I would go with answering 7 and 8 if I were you. Hoped this helped!