Suppose you are deciding how many slices of pizza to eat for lunch. The first slice of pizza gives you $7 worth of enjoyment, the second slice gives you $5 worth of enjoyment, the third $3 worth of enjoyment, the fourth $1 worth of enjoyment, and any additional slices of pizza give you $0 worth of enjoyment, or no marginal benefit. If it costs $4.50 to purchase a slice of pizza, what is the optimal number of pizza slices to buy