Pharmacology In Exercises 15 and 16, use the graph, which shows the average prices of name brand and generic drug prescriptions in the United States. (Source: National Association of Chain Drug Stores) 120- 100- 80- Average price (in dollars) Name brand 60 . Generic 20 - . X 2000 2001 2002 2003 2004 2005 2006 2007 Year 15. Is the average price of a name brand prescription a function of the year? Is the average price of a generic prescription a function of the year? Explain. 16. Let b(t) and g(t) represent the average prices of name brand and generic prescriptions, respectively, in year t. Find b(2007) and g(2000).Testing for Functions Represented Algebraically In Exercises 17-28, determine whether the equation represents y as a function of x. 17. x2 + y? = 4 18. x = y2+1 19. y = VX - 1 20. y = vx+5 21. 2x + 3y = 4 22. x = -y +5 23. y2 = x2 - 1 24. x+y = 3 25. y = 4 - x 26. y| = 4 - X 27. X = -7 28. y = 8Evaluating a Function In Exercises 29-44, evaluate the function at each specified value of the independent variable and simplify. 29. f (t) = 3t + 1 (a) f(2) (b) f (-4) (c) f (t + 2)