In a statistics class, a linear regression equation was used to predict the number of hours a student needs to study to achieve a certain test score. The equation was \( y = 2.5 + 0.75x \), where \( y \) is the predicted number of hours of study and \( x \) is the test score. If a student wants to score 80 on the test, how many hours should they study according to the model? Let's think step by step and output the final answer within \boxed{}.
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