The director of a college theater company is trying to forecast the demand for tickets to her new play. She hired an economic consulting firm and the economists identified two groups of demanders -- the general non-university public (Q_{Public) and students (}Q_Students) and estimated each group's demand relationship:

Q_Public= 500 - 5P

Q_Students= 200 - 4P

where Q_Publicand Q_Studentsare the quantity demanded by each group and P represents the price per ticket. What is the market demand relationship (or function)?